diff --git a/VERSION b/VERSION
index 89c5dab..a2f00ca 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-0.1.0-dev15
+0.1.0-dev16
diff --git a/src/ccma/services/reminder_mail.py b/src/ccma/services/reminder_mail.py
index ac43f74..3dbe7d2 100644
--- a/src/ccma/services/reminder_mail.py
+++ b/src/ccma/services/reminder_mail.py
@@ -158,29 +158,39 @@ def generate_and_send_reminder_mail(
             raise RepositoryError(f"Die Ausgabedatei existiert bereits: {target}")
 
     sent_reminder = repository.mark_reminder_sent(member_id, claim_id, reminder_id)
-    updated_data, updated_claim = repository.get_claim(member_id, claim_id)
-    organization = repository.get_configuration().get("organization") or {}
-    content = reminder_mail_bytes(
-        repository,
-        member=member,
-        reminder=sent_reminder,
-        claim=updated_claim,
-        balance=f"{claim_balance(updated_data, updated_claim):.2f}",
-        organization=organization,
-        sender_name=sender_name,
-        sender_email=sender_email,
-        signature=signature,
-    )
-    archive_dir = repository.members_root / member_id / "files" / "documents" / "Mahnungen"
-    archive_dir.mkdir(parents=True, exist_ok=True)
-    filename = (
-        f"{datetime.now().date().isoformat()}-"
-        f"{_safe_filename(str(sent_reminder.get('name', 'Mahnung')))}.eml"
-    )
-    archive_path = _available_path(archive_dir, filename)
-    archive_temp = archive_path.with_name(f".{archive_path.name}.tmp")
     export_path: Path | None = None
+    # Once the mail has actually left the building -- landed on the SMTP server, been
+    # filed into an IMAP folder, or been written to the local export file -- it must
+    # not be un-sent again: a later failure (Sent-folder copy, moving the archive file
+    # into place) can no longer roll the reminder back to "draft", or a retry could
+    # send/file the same Mahnung a second time and double-book its fee. Everything
+    # before that point -- including preparing the archive directory/path -- still
+    # rolls back on failure, since nothing has actually gone out yet.
+    delivered = False
+    archive_failure: Exception | None = None
+    archive_temp: Path | None = None
     try:
+        updated_data, updated_claim = repository.get_claim(member_id, claim_id)
+        organization = repository.get_configuration().get("organization") or {}
+        content = reminder_mail_bytes(
+            repository,
+            member=member,
+            reminder=sent_reminder,
+            claim=updated_claim,
+            balance=f"{claim_balance(updated_data, updated_claim):.2f}",
+            organization=organization,
+            sender_name=sender_name,
+            sender_email=sender_email,
+            signature=signature,
+        )
+        archive_dir = repository.members_root / member_id / "files" / "documents" / "Mahnungen"
+        archive_dir.mkdir(parents=True, exist_ok=True)
+        filename = (
+            f"{datetime.now().date().isoformat()}-"
+            f"{_safe_filename(str(sent_reminder.get('name', 'Mahnung')))}.eml"
+        )
+        archive_path = _available_path(archive_dir, filename)
+        archive_temp = archive_path.with_name(f".{archive_path.name}.tmp")
         archive_temp.write_bytes(content)
         if delivery_mode == "local":
             export_temp = target.with_name(f".{target.name}.tmp")
@@ -190,11 +200,13 @@ def generate_and_send_reminder_mail(
             finally:
                 export_temp.unlink(missing_ok=True)
             export_path = target
+            delivered = True
         elif delivery_mode == "send":
             settings = repository.get_email_settings()
             sent_copy = imap_session(settings) if settings["imap_sent_enabled"] else nullcontext(None)
             with smtp_session(settings) as smtp_client, sent_copy as imap_client:
                 send_via_smtp(smtp_client, content)
+                delivered = True
                 if imap_client is not None:
                     ensure_imap_folder(imap_client, settings["imap_sent_folder"])
                     append_message(
@@ -205,29 +217,45 @@ def generate_and_send_reminder_mail(
             with imap_session(settings) as client:
                 ensure_imap_folder(client, settings["imap_drafts_folder"])
                 append_message(client, content, folder=settings["imap_drafts_folder"], flags=r"(\Draft)")
+                delivered = True
         os.replace(archive_temp, archive_path)
-    finally:
-        archive_temp.unlink(missing_ok=True)
-    relative_path = archive_path.relative_to(
-        repository.members_root / member_id / "files"
-    ).as_posix()
+    except Exception as exc:
+        if archive_temp is not None:
+            archive_temp.unlink(missing_ok=True)
+        if not delivered:
+            repository.revert_reminder_sent(member_id, claim_id, reminder_id)
+            raise
+        archive_failure = exc
+
     digest = hashlib.sha256(content).hexdigest()
+    references = {"claim_id": claim_id, "reminder_id": reminder_id}
+    if archive_failure is None:
+        references["document"] = archive_path.relative_to(
+            repository.members_root / member_id / "files"
+        ).as_posix()
+    data = {
+        "recipient": member.email,
+        "sha256": digest,
+        "payment_deadline": str(sent_reminder.get("payment_deadline", "")),
+        "delivery_mode": delivery_mode,
+    }
+    if archive_failure is not None:
+        data["archive_error"] = str(archive_failure)
+    # Log the event even when archiving failed -- the mail was already delivered/filed,
+    # so this must stay a traceable "sent" record instead of silently vanishing.
     repository.append_event(
         member_id,
         event_type="reminder_email_sent",
         summary=f"Mahnung per E-Mail versandt: {sent_reminder.get('name', '')}",
         actor_type="user",
         actor_name="Vorstand",
-        references={
-            "claim_id": claim_id,
-            "reminder_id": reminder_id,
-            "document": relative_path,
-        },
-        data={
-            "recipient": member.email,
-            "sha256": digest,
-            "payment_deadline": str(sent_reminder.get("payment_deadline", "")),
-            "delivery_mode": delivery_mode,
-        },
+        references=references,
+        data=data,
     )
+    if archive_failure is not None:
+        raise RepositoryError(
+            "Die Mahnung wurde zugestellt bzw. abgelegt, konnte aber nicht vollständig "
+            f"archiviert werden: {archive_failure}. Die Mahnung bleibt als versandt gebucht "
+            "-- bitte die Mitgliedsakte manuell prüfen."
+        ) from archive_failure
     return GeneratedReminderMail(export_path, archive_path, digest)
diff --git a/src/ccma/services/sepa_mail.py b/src/ccma/services/sepa_mail.py
index 573aec2..f603e46 100644
--- a/src/ccma/services/sepa_mail.py
+++ b/src/ccma/services/sepa_mail.py
@@ -127,61 +127,87 @@ def generate_debit_mails(
             if not member.email.strip():
                 warnings.append(f"{member.member_number or member.display_name}: E-Mail-Adresse fehlt.")
                 continue
-            content = debit_mail_bytes(
-                repository,
-                member=member,
-                debit=debit,
-                collection_date=collection_date,
-                organization=organization,
-                sender_name=sender_name,
-                sender_email=sender_email,
-                signature=signature,
-            )
-            filename = (
-                f"SEPA-Info-{collection_date.isoformat()}-"
-                f"{_safe_filename(member.member_number or member.display_name)}.eml"
-            )
-            archive_dir = repository.members_root / member.member_id / "files" / "documents" / "SEPA"
-            archive_dir.mkdir(parents=True, exist_ok=True)
-            archive_path = _available_path(archive_dir, filename)
             export_path: Path | None = None
-            if delivery_mode == "local":
-                export_path = _available_path(output, filename)
-                export_path.write_bytes(content)
-            elif delivery_mode == "send":
-                send_via_smtp(smtp_client, content)
-                if imap_client is not None:
-                    append_message(
-                        imap_client, content, folder=email_settings["imap_sent_folder"], flags=r"(\Seen)"
-                    )
-            else:
-                append_message(
-                    imap_client, content, folder=email_settings["imap_drafts_folder"], flags=r"(\Draft)"
-                )
+            archive_path: Path | None = None
+            # Once the mail has actually left the building for this debit -- SMTP
+            # accepted it, it's filed in the IMAP folder, or the local export file was
+            # written -- a later archiving failure must not abort the whole batch and
+            # lose track of the fact that this one was already delivered; nor may it
+            # abort earlier/later debits that have nothing to do with this failure.
+            delivered = False
+            archive_failure: Exception | None = None
             try:
+                content = debit_mail_bytes(
+                    repository,
+                    member=member,
+                    debit=debit,
+                    collection_date=collection_date,
+                    organization=organization,
+                    sender_name=sender_name,
+                    sender_email=sender_email,
+                    signature=signature,
+                )
+                filename = (
+                    f"SEPA-Info-{collection_date.isoformat()}-"
+                    f"{_safe_filename(member.member_number or member.display_name)}.eml"
+                )
+                archive_dir = (
+                    repository.members_root / member.member_id / "files" / "documents" / "SEPA"
+                )
+                archive_dir.mkdir(parents=True, exist_ok=True)
+                archive_path = _available_path(archive_dir, filename)
+                if delivery_mode == "local":
+                    export_path = _available_path(output, filename)
+                    export_path.write_bytes(content)
+                    delivered = True
+                elif delivery_mode == "send":
+                    send_via_smtp(smtp_client, content)
+                    delivered = True
+                    if imap_client is not None:
+                        append_message(
+                            imap_client, content, folder=email_settings["imap_sent_folder"], flags=r"(\Seen)"
+                        )
+                else:
+                    append_message(
+                        imap_client, content, folder=email_settings["imap_drafts_folder"], flags=r"(\Draft)"
+                    )
+                    delivered = True
                 archive_path.write_bytes(content)
-            except OSError:
-                if export_path is not None:
-                    export_path.unlink(missing_ok=True)
-                raise
-            relative_path = archive_path.relative_to(
-                repository.members_root / member.member_id / "files"
-            ).as_posix()
+            except (OSError, RepositoryError) as exc:
+                if not delivered:
+                    if export_path is not None:
+                        export_path.unlink(missing_ok=True)
+                    warnings.append(f"{member.member_number or member.display_name}: {exc}")
+                    continue
+                warnings.append(
+                    f"{member.member_number or member.display_name}: E-Mail wurde versandt/abgelegt, "
+                    f"konnte aber nicht archiviert werden ({exc}); bitte manuell prüfen."
+                )
+                archive_failure = exc
+
             digest = hashlib.sha256(content).hexdigest()
+            references = {}
+            if archive_failure is None:
+                references["document"] = archive_path.relative_to(
+                    repository.members_root / member.member_id / "files"
+                ).as_posix()
+            data = {
+                "sha256": digest,
+                "recipient": member.email,
+                "collection_date": collection_date.isoformat(),
+                "amount": f"{debit.amount:.2f}",
+                "delivery_mode": delivery_mode,
+            }
+            if archive_failure is not None:
+                data["archive_error"] = str(archive_failure)
             repository.append_event(
                 member.member_id,
                 event_type="sepa_notification_generated",
                 summary=f"SEPA-Info-Mail erzeugt: {archive_path.name}",
                 actor_type="user",
                 actor_name="Vorstand",
-                references={"document": relative_path},
-                data={
-                    "sha256": digest,
-                    "recipient": member.email,
-                    "collection_date": collection_date.isoformat(),
-                    "amount": f"{debit.amount:.2f}",
-                    "delivery_mode": delivery_mode,
-                },
+                references=references,
+                data=data,
             )
             generated.append(
                 GeneratedDebitMail(member.member_id, member.email, export_path, archive_path)
diff --git a/src/ccma/services/welcome_mail.py b/src/ccma/services/welcome_mail.py
index d2fea40..6ef0d41 100644
--- a/src/ccma/services/welcome_mail.py
+++ b/src/ccma/services/welcome_mail.py
@@ -175,12 +175,20 @@ def generate_and_send_welcome_mail(
         sender_email=sender_email,
         signature=signature,
     )
-    archive_dir = repository.members_root / member_id / "files" / "documents" / "Willkommen"
-    archive_dir.mkdir(parents=True, exist_ok=True)
-    archive_path = _available_path(archive_dir, f"{date.today().isoformat()}-Willkommen.eml")
-    archive_temp = archive_path.with_name(f".{archive_path.name}.tmp")
     export_path: Path | None = None
+    archive_path: Path | None = None
+    archive_temp: Path | None = None
+    # Same rule as the dunning/SEPA mails: once the mail has reached the SMTP server,
+    # the IMAP folder or the local export file, a later archiving failure must not
+    # hide that it went out -- the event is written either way and the archiving
+    # problem is reported afterwards.
+    delivered = False
+    archive_failure: Exception | None = None
     try:
+        archive_dir = repository.members_root / member_id / "files" / "documents" / "Willkommen"
+        archive_dir.mkdir(parents=True, exist_ok=True)
+        archive_path = _available_path(archive_dir, f"{date.today().isoformat()}-Willkommen.eml")
+        archive_temp = archive_path.with_name(f".{archive_path.name}.tmp")
         archive_temp.write_bytes(content)
         if delivery_mode == "local":
             export_temp = target.with_name(f".{target.name}.tmp")
@@ -190,11 +198,13 @@ def generate_and_send_welcome_mail(
             finally:
                 export_temp.unlink(missing_ok=True)
             export_path = target
+            delivered = True
         elif delivery_mode == "send":
             settings = repository.get_email_settings()
             sent_copy = imap_session(settings) if settings["imap_sent_enabled"] else nullcontext(None)
             with smtp_session(settings) as smtp_client, sent_copy as imap_client:
                 send_via_smtp(smtp_client, content)
+                delivered = True
                 if imap_client is not None:
                     ensure_imap_folder(imap_client, settings["imap_sent_folder"])
                     append_message(
@@ -207,27 +217,44 @@ def generate_and_send_welcome_mail(
                 append_message(
                     client, content, folder=settings["imap_drafts_folder"], flags=r"(\Draft)"
                 )
+                delivered = True
         os.replace(archive_temp, archive_path)
-    finally:
-        archive_temp.unlink(missing_ok=True)
-    relative_path = archive_path.relative_to(
-        repository.members_root / member_id / "files"
-    ).as_posix()
+    except Exception as exc:
+        if archive_temp is not None:
+            archive_temp.unlink(missing_ok=True)
+        if not delivered:
+            raise
+        archive_failure = exc
+
     digest = hashlib.sha256(content).hexdigest()
+    references: dict[str, str] = {}
+    if archive_failure is None:
+        references["document"] = archive_path.relative_to(
+            repository.members_root / member_id / "files"
+        ).as_posix()
+    event_data = {
+        "recipient": member.email,
+        "sha256": digest,
+        "claim_ids": [str(claim.get("claim_id", "")) for claim in claims],
+        "delivery_mode": delivery_mode,
+    }
+    if archive_failure is not None:
+        event_data["archive_error"] = str(archive_failure)
     repository.append_event(
         member_id,
         event_type="welcome_email_sent",
         summary="Willkommens- und Erstrechnungsmail erzeugt",
         actor_type="user",
         actor_name="Vorstand",
-        references={"document": relative_path},
-        data={
-            "recipient": member.email,
-            "sha256": digest,
-            "claim_ids": [str(claim.get("claim_id", "")) for claim in claims],
-            "delivery_mode": delivery_mode,
-        },
+        references=references,
+        data=event_data,
     )
+    if archive_failure is not None:
+        raise RepositoryError(
+            "Die Willkommensmail wurde zugestellt bzw. abgelegt, konnte aber nicht "
+            f"vollständig archiviert werden: {archive_failure}. Bitte die Mitgliedsakte "
+            "manuell prüfen."
+        ) from archive_failure
     return GeneratedWelcomeMail(export_path, archive_path, digest)
 
 
diff --git a/tests/test_reminder_mail.py b/tests/test_reminder_mail.py
index 985ea43..318c178 100644
--- a/tests/test_reminder_mail.py
+++ b/tests/test_reminder_mail.py
@@ -2,9 +2,11 @@ from contextlib import contextmanager
 from email.parser import BytesParser
 from email.policy import default
 
+import pytest
 from test_reminders import _overdue_claim_repository
 
 from ccma.services.reminder_mail import generate_and_send_reminder_mail
+from ccma.storage.repository import RepositoryError
 
 
 def test_reminder_mail_is_archived_and_marks_reminder_sent(tmp_path):
@@ -200,3 +202,214 @@ def test_reminder_mail_send_mode_also_copies_to_sent_folder_when_enabled(tmp_pat
 
     assert ensured == [("imap-client", "INBOX.Gesendet")]
     assert appended == [("imap-client", "INBOX.Gesendet", r"(\Seen)")]
+
+
+def test_reminder_mail_send_failure_reverts_sent_status(tmp_path, monkeypatch):
+    import ccma.services.reminder_mail as reminder_mail_module
+
+    repository, member = _overdue_claim_repository(tmp_path / "store")
+    member.email = "reminder@example.org"
+    repository.save_member(member)
+    repository.save_email_settings(
+        delivery_mode="send",
+        smtp_host="mail.example.org",
+        smtp_port=587,
+        smtp_security="none",
+        smtp_username="",
+        smtp_password="",
+        imap_host="",
+        imap_port=993,
+        imap_security="ssl",
+        imap_username="",
+        imap_password="",
+        imap_drafts_folder="",
+    )
+    reminder = repository.create_reminder_draft(
+        member.member_id,
+        "claim-1",
+        level=1,
+        name="Zahlungserinnerung",
+        payment_deadline_days=14,
+        items=[{"description": "Mahngebühr", "amount": "5.00"}],
+    )
+
+    @contextmanager
+    def _fake_smtp_session(settings):
+        yield "smtp-client"
+
+    monkeypatch.setattr(reminder_mail_module, "smtp_session", _fake_smtp_session)
+
+    def _failing_send(client, content):
+        raise RepositoryError("E-Mail konnte nicht versandt werden: connection reset")
+
+    monkeypatch.setattr(reminder_mail_module, "send_via_smtp", _failing_send)
+
+    with pytest.raises(RepositoryError):
+        generate_and_send_reminder_mail(
+            repository,
+            member.member_id,
+            "claim-1",
+            reminder["reminder_id"],
+            delivery_mode="send",
+            sender_name="Verwaltung C3MA",
+            sender_email="verwaltung@example.org",
+            signature="Der Vorstand",
+        )
+
+    data = repository.get_contributions(member.member_id)
+    stored_reminder = data.reminders[0]
+    assert stored_reminder["status"] == "draft"
+    assert not stored_reminder.get("fee_item_ids")
+    assert repository.get_events(member.member_id)[-1].event_type == "reminder_sent_reverted"
+    _data, claim = repository.get_claim(member.member_id, "claim-1")
+    assert not any(
+        item.get("description") == "Mahngebühr" for item in claim.get("items", [])
+    )
+
+
+def test_reminder_mail_local_write_failure_reverts_sent_status(tmp_path, monkeypatch):
+    repository, member = _overdue_claim_repository(tmp_path / "store")
+    member.email = "reminder@example.org"
+    repository.save_member(member)
+    reminder = repository.create_reminder_draft(
+        member.member_id,
+        "claim-1",
+        level=1,
+        name="Zahlungserinnerung",
+        payment_deadline_days=14,
+    )
+
+    import ccma.services.reminder_mail as reminder_mail_module
+
+    def _boom(*args, **kwargs):
+        raise OSError("disk full")
+
+    monkeypatch.setattr(reminder_mail_module.os, "replace", _boom)
+
+    with pytest.raises(OSError):
+        generate_and_send_reminder_mail(
+            repository,
+            member.member_id,
+            "claim-1",
+            reminder["reminder_id"],
+            delivery_mode="local",
+            output_path=tmp_path / "Zahlungserinnerung.eml",
+            sender_name="Verwaltung C3MA",
+            sender_email="verwaltung@example.org",
+            signature="Der Vorstand",
+        )
+
+    data = repository.get_contributions(member.member_id)
+    assert data.reminders[0]["status"] == "draft"
+
+
+def test_reminder_mail_archiving_failure_after_smtp_success_does_not_revert(tmp_path, monkeypatch):
+    import ccma.services.reminder_mail as reminder_mail_module
+
+    repository, member = _overdue_claim_repository(tmp_path / "store")
+    member.email = "reminder@example.org"
+    repository.save_member(member)
+    repository.save_email_settings(
+        delivery_mode="send",
+        smtp_host="mail.example.org",
+        smtp_port=587,
+        smtp_security="none",
+        smtp_username="",
+        smtp_password="",
+        imap_host="",
+        imap_port=993,
+        imap_security="ssl",
+        imap_username="",
+        imap_password="",
+        imap_drafts_folder="",
+    )
+    reminder = repository.create_reminder_draft(
+        member.member_id,
+        "claim-1",
+        level=1,
+        name="Zahlungserinnerung",
+        payment_deadline_days=14,
+        items=[{"description": "Mahngebühr", "amount": "5.00"}],
+    )
+
+    @contextmanager
+    def _fake_smtp_session(settings):
+        yield "smtp-client"
+
+    monkeypatch.setattr(reminder_mail_module, "smtp_session", _fake_smtp_session)
+    monkeypatch.setattr(reminder_mail_module, "send_via_smtp", lambda client, content: None)
+
+    real_replace = reminder_mail_module.os.replace
+
+    def _flaky_replace(src, dst):
+        # Only the final archive move (into the "Mahnungen" folder) should fail --
+        # the mail has already been handed to send_via_smtp by that point.
+        if str(dst).endswith(".eml") and "Mahnungen" in str(dst):
+            raise OSError("disk full")
+        return real_replace(src, dst)
+
+    monkeypatch.setattr(reminder_mail_module.os, "replace", _flaky_replace)
+
+    with pytest.raises(RepositoryError, match="zugestellt"):
+        generate_and_send_reminder_mail(
+            repository,
+            member.member_id,
+            "claim-1",
+            reminder["reminder_id"],
+            delivery_mode="send",
+            sender_name="Verwaltung C3MA",
+            sender_email="verwaltung@example.org",
+            signature="Der Vorstand",
+        )
+
+    data = repository.get_contributions(member.member_id)
+    stored_reminder = data.reminders[0]
+    assert stored_reminder["status"] == "sent", "mail was already sent -- must not be un-sent"
+    assert stored_reminder.get("fee_item_ids")
+    events = repository.get_events(member.member_id)
+    assert events[-1].event_type == "reminder_email_sent"
+    assert events[-1].data["archive_error"]
+    assert "document" not in events[-1].references
+
+
+def test_reminder_mail_archive_dir_creation_failure_reverts_sent_status(tmp_path, monkeypatch):
+    from pathlib import Path
+
+    repository, member = _overdue_claim_repository(tmp_path / "store")
+    member.email = "reminder@example.org"
+    repository.save_member(member)
+    reminder = repository.create_reminder_draft(
+        member.member_id,
+        "claim-1",
+        level=1,
+        name="Zahlungserinnerung",
+        payment_deadline_days=14,
+        items=[{"description": "Mahngebühr", "amount": "5.00"}],
+    )
+
+    original_mkdir = Path.mkdir
+
+    def _flaky_mkdir(self, *args, **kwargs):
+        if self.name == "Mahnungen":
+            raise OSError("permission denied")
+        return original_mkdir(self, *args, **kwargs)
+
+    monkeypatch.setattr(Path, "mkdir", _flaky_mkdir)
+
+    with pytest.raises(OSError):
+        generate_and_send_reminder_mail(
+            repository,
+            member.member_id,
+            "claim-1",
+            reminder["reminder_id"],
+            delivery_mode="local",
+            output_path=tmp_path / "Zahlungserinnerung.eml",
+            sender_name="Verwaltung C3MA",
+            sender_email="verwaltung@example.org",
+            signature="Der Vorstand",
+        )
+
+    data = repository.get_contributions(member.member_id)
+    stored_reminder = data.reminders[0]
+    assert stored_reminder["status"] == "draft"
+    assert not stored_reminder.get("fee_item_ids")
diff --git a/tests/test_sepa.py b/tests/test_sepa.py
index f3bc2ed..48f91fc 100644
--- a/tests/test_sepa.py
+++ b/tests/test_sepa.py
@@ -388,3 +388,288 @@ def test_generated_mail_send_mode_copies_to_sent_folder_reusing_one_imap_connect
     assert len(imap_connections) == 1, "one IMAP connection should be reused for the whole batch"
     assert ensured == ["INBOX.Gesendet"]
     assert appended == [("imap-client", "INBOX.Gesendet", r"(\Seen)")] * 2
+
+
+def test_generated_mail_archiving_failure_after_smtp_success_keeps_batch_going(tmp_path, monkeypatch):
+    import ccma.services.sepa_mail as sepa_mail_module
+
+    repository, ada = _repository(tmp_path)
+    second = repository.create_member(first_name="Grace", last_name="Hopper", member_number="C3-43")
+    second.status = "active"
+    second.email = "grace@example.org"
+    second.account_holder = "Grace Hopper"
+    second.iban = "DE89370400440532013000"
+    second.bic = "COBADEFFXXX"
+    second.mandate_reference = "MANDAT-43"
+    second.mandate_signed_at = "2025-01-10"
+    second.mandate_active = True
+    repository.save_member(second)
+    repository.save_contributions(
+        second.member_id,
+        ContributionData(
+            claims=[
+                {
+                    "claim_id": "due",
+                    "title": "Mitgliedsbeitrag 2026",
+                    "amount": "150.00",
+                    "due_date": "2026-01-31",
+                    "status": "open",
+                }
+            ]
+        ),
+    )
+    organization = repository.get_configuration()["organization"]
+    organization.update(
+        {
+            "name": "Chaos Computer Club Mannheim e.V.",
+            "email": "verwaltung@example.org",
+            "iban": "DE89370400440532013000",
+            "bic": "COBADEFFXXX",
+            "creditor_id": "DE98ZZZ09999999999",
+        }
+    )
+    repository.save_organization(organization)
+    repository.save_email_settings(
+        delivery_mode="send",
+        smtp_host="mail.example.org",
+        smtp_port=587,
+        smtp_security="none",
+        smtp_username="",
+        smtp_password="",
+        imap_host="",
+        imap_port=993,
+        imap_security="ssl",
+        imap_username="",
+        imap_password="",
+        imap_drafts_folder="",
+    )
+    debits, _warnings = pending_direct_debits(repository, due_until=date(2026, 12, 31))
+    assert len(debits) == 2
+
+    monkeypatch.setattr(
+        sepa_mail_module, "smtp_session", contextmanager(lambda settings: iter(["smtp-client"]))
+    )
+    sent = []
+    monkeypatch.setattr(sepa_mail_module, "send_via_smtp", lambda client, content: sent.append(content))
+
+    from pathlib import Path
+
+    original_write_bytes = Path.write_bytes
+
+    def _flaky_write_bytes(self, data):
+        if "documents" in str(self) and "C3-43" in self.name:
+            raise OSError("disk full")
+        return original_write_bytes(self, data)
+
+    monkeypatch.setattr(Path, "write_bytes", _flaky_write_bytes)
+
+    generated, warnings = generate_debit_mails(
+        repository,
+        debits,
+        collection_date=date(2026, 8, 3),
+        delivery_mode="send",
+        sender_name="Verwaltung C3MA",
+        sender_email="verwaltung@example.org",
+        signature="Der Vorstand",
+    )
+
+    # Both mails were handed to SMTP -- a broken archive write for one of them must
+    # not swallow the other, nor pretend the failing one was never sent.
+    assert len(sent) == 2
+    assert len(generated) == 2
+    assert len(warnings) == 1
+    assert "C3-43" in warnings[0] or "Grace" in warnings[0]
+
+    failing = next(g for g in generated if g.member_id == second.member_id)
+    assert not failing.archive_path.is_file()
+    succeeding = next(g for g in generated if g.member_id == ada.member_id)
+    assert succeeding.archive_path.is_file()
+
+    grace_event = repository.get_events(second.member_id)[-1]
+    assert grace_event.event_type == "sepa_notification_generated"
+    assert grace_event.data["archive_error"]
+    assert "document" not in grace_event.references
+    ada_event = repository.get_events(ada.member_id)[-1]
+    assert "document" in ada_event.references
+
+
+def test_generated_mail_smtp_failure_for_one_debit_does_not_abort_the_batch(tmp_path, monkeypatch):
+    import ccma.services.sepa_mail as sepa_mail_module
+    from ccma.storage.repository import RepositoryError
+
+    repository, ada = _repository(tmp_path)
+    second = repository.create_member(first_name="Grace", last_name="Hopper", member_number="C3-43")
+    second.status = "active"
+    second.email = "grace@example.org"
+    second.account_holder = "Grace Hopper"
+    second.iban = "DE89370400440532013000"
+    second.bic = "COBADEFFXXX"
+    second.mandate_reference = "MANDAT-43"
+    second.mandate_signed_at = "2025-01-10"
+    second.mandate_active = True
+    repository.save_member(second)
+    repository.save_contributions(
+        second.member_id,
+        ContributionData(
+            claims=[
+                {
+                    "claim_id": "due",
+                    "title": "Mitgliedsbeitrag 2026",
+                    "amount": "150.00",
+                    "due_date": "2026-01-31",
+                    "status": "open",
+                }
+            ]
+        ),
+    )
+    organization = repository.get_configuration()["organization"]
+    organization.update(
+        {
+            "name": "Chaos Computer Club Mannheim e.V.",
+            "email": "verwaltung@example.org",
+            "iban": "DE89370400440532013000",
+            "bic": "COBADEFFXXX",
+            "creditor_id": "DE98ZZZ09999999999",
+        }
+    )
+    repository.save_organization(organization)
+    repository.save_email_settings(
+        delivery_mode="send",
+        smtp_host="mail.example.org",
+        smtp_port=587,
+        smtp_security="none",
+        smtp_username="",
+        smtp_password="",
+        imap_host="",
+        imap_port=993,
+        imap_security="ssl",
+        imap_username="",
+        imap_password="",
+        imap_drafts_folder="",
+    )
+    debits, _warnings = pending_direct_debits(repository, due_until=date(2026, 12, 31))
+    assert len(debits) == 2
+
+    monkeypatch.setattr(
+        sepa_mail_module, "smtp_session", contextmanager(lambda settings: iter(["smtp-client"]))
+    )
+    sent = []
+
+    def _flaky_send(client, content):
+        if b"ada@example.org" in content:
+            raise RepositoryError("E-Mail konnte nicht versandt werden: connection reset")
+        sent.append(content)
+
+    monkeypatch.setattr(sepa_mail_module, "send_via_smtp", _flaky_send)
+
+    generated, warnings = generate_debit_mails(
+        repository,
+        debits,
+        collection_date=date(2026, 8, 3),
+        delivery_mode="send",
+        sender_name="Verwaltung C3MA",
+        sender_email="verwaltung@example.org",
+        signature="Der Vorstand",
+    )
+
+    assert len(sent) == 1
+    assert len(generated) == 1
+    assert generated[0].member_id == second.member_id
+    assert len(warnings) == 1
+    assert "connection reset" in warnings[0]
+    ada_events = repository.get_events(ada.member_id)
+    assert all(event.event_type != "sepa_notification_generated" for event in ada_events)
+
+
+def test_generated_mail_archive_dir_creation_failure_for_one_debit_does_not_abort_the_batch(
+    tmp_path, monkeypatch
+):
+    from pathlib import Path
+
+    repository, ada = _repository(tmp_path)
+    second = repository.create_member(first_name="Grace", last_name="Hopper", member_number="C3-43")
+    second.status = "active"
+    second.email = "grace@example.org"
+    second.account_holder = "Grace Hopper"
+    second.iban = "DE89370400440532013000"
+    second.bic = "COBADEFFXXX"
+    second.mandate_reference = "MANDAT-43"
+    second.mandate_signed_at = "2025-01-10"
+    second.mandate_active = True
+    repository.save_member(second)
+    repository.save_contributions(
+        second.member_id,
+        ContributionData(
+            claims=[
+                {
+                    "claim_id": "due",
+                    "title": "Mitgliedsbeitrag 2026",
+                    "amount": "150.00",
+                    "due_date": "2026-01-31",
+                    "status": "open",
+                }
+            ]
+        ),
+    )
+    organization = repository.get_configuration()["organization"]
+    organization.update(
+        {
+            "name": "Chaos Computer Club Mannheim e.V.",
+            "email": "verwaltung@example.org",
+            "iban": "DE89370400440532013000",
+            "bic": "COBADEFFXXX",
+            "creditor_id": "DE98ZZZ09999999999",
+        }
+    )
+    repository.save_organization(organization)
+    repository.save_email_settings(
+        delivery_mode="send",
+        smtp_host="mail.example.org",
+        smtp_port=587,
+        smtp_security="none",
+        smtp_username="",
+        smtp_password="",
+        imap_host="",
+        imap_port=993,
+        imap_security="ssl",
+        imap_username="",
+        imap_password="",
+        imap_drafts_folder="",
+    )
+    debits, _warnings = pending_direct_debits(repository, due_until=date(2026, 12, 31))
+    assert len(debits) == 2
+
+    import ccma.services.sepa_mail as sepa_mail_module
+
+    monkeypatch.setattr(
+        sepa_mail_module, "smtp_session", contextmanager(lambda settings: iter(["smtp-client"]))
+    )
+    sent = []
+    monkeypatch.setattr(sepa_mail_module, "send_via_smtp", lambda client, content: sent.append(content))
+
+    original_mkdir = Path.mkdir
+
+    def _flaky_mkdir(self, *args, **kwargs):
+        if self.name == "SEPA" and second.member_id in str(self):
+            raise OSError("permission denied")
+        return original_mkdir(self, *args, **kwargs)
+
+    monkeypatch.setattr(Path, "mkdir", _flaky_mkdir)
+
+    generated, warnings = generate_debit_mails(
+        repository,
+        debits,
+        collection_date=date(2026, 8, 3),
+        delivery_mode="send",
+        sender_name="Verwaltung C3MA",
+        sender_email="verwaltung@example.org",
+        signature="Der Vorstand",
+    )
+
+    # Grace's archive directory could not even be created -- nothing was sent to her,
+    # so she must NOT show up as delivered, but Ada's mail must still go out.
+    assert len(sent) == 1
+    assert len(generated) == 1
+    assert generated[0].member_id == ada.member_id
+    assert len(warnings) == 1
+    assert "Grace" in warnings[0] or "C3-43" in warnings[0]
diff --git a/tests/test_welcome_mail.py b/tests/test_welcome_mail.py
index 1178018..4da56f0 100644
--- a/tests/test_welcome_mail.py
+++ b/tests/test_welcome_mail.py
@@ -219,3 +219,51 @@ def test_member_without_email_is_refused(tmp_path):
             sender_email="verwaltung@example.org",
             signature="Der Vorstand",
         )
+
+
+def test_archiving_failure_after_smtp_success_still_logs_the_sent_mail(tmp_path, monkeypatch):
+    import ccma.services.welcome_mail as welcome_mail_module
+
+    repository, member = _new_member_repository(tmp_path)
+    repository.save_email_settings(
+        delivery_mode="send",
+        smtp_host="mail.example.org",
+        smtp_port=587,
+        smtp_security="none",
+        smtp_username="",
+        smtp_password="",
+        imap_host="",
+        imap_port=993,
+        imap_security="ssl",
+        imap_username="",
+        imap_password="",
+        imap_drafts_folder="",
+    )
+    monkeypatch.setattr(
+        welcome_mail_module, "smtp_session", contextmanager(lambda settings: iter(["client"]))
+    )
+    monkeypatch.setattr(welcome_mail_module, "send_via_smtp", lambda client, content: None)
+    real_replace = welcome_mail_module.os.replace
+
+    def _flaky_replace(src, dst):
+        # Only the final move into the member file fails -- the mail is out by then.
+        if str(dst).endswith(".eml") and "Willkommen" in str(dst):
+            raise OSError("disk full")
+        return real_replace(src, dst)
+
+    monkeypatch.setattr(welcome_mail_module.os, "replace", _flaky_replace)
+
+    with pytest.raises(RepositoryError, match="zugestellt"):
+        generate_and_send_welcome_mail(
+            repository,
+            member.member_id,
+            delivery_mode="send",
+            sender_name="Verwaltung C3MA",
+            sender_email="verwaltung@example.org",
+            signature="Der Vorstand",
+        )
+
+    event = repository.get_events(member.member_id)[-1]
+    assert event.event_type == "welcome_email_sent"
+    assert event.data["archive_error"]
+    assert "document" not in event.references