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Remove DKIM-Signature from incoming mail after checking #533

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3 changes: 3 additions & 0 deletions CHANGELOG.md
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,9 @@

## untagged

- Remove `DKIM-Signature` from incoming mails after verifying
([#530](https://github.com/chatmail/server/pull/530))

- Send SNI when connecting to outside servers
([#524](https://github.com/chatmail/server/pull/524))

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16 changes: 13 additions & 3 deletions cmdeploy/src/cmdeploy/__init__.py
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Expand Up @@ -228,7 +228,6 @@ def _configure_opendkim(domain: str, dkim_selector: str = "dkim") -> bool:
)
need_restart |= service_file.changed


return need_restart


Expand Down Expand Up @@ -275,7 +274,18 @@ def _configure_postfix(config: Config, debug: bool = False) -> bool:
)
need_restart |= master_config.changed

header_cleanup = files.put(
incoming_header_cleanup = files.put(
src=importlib.resources.files(__package__).joinpath(
"postfix/incoming_header_cleanup"
),
dest="/etc/postfix/incoming_header_cleanup",
user="root",
group="root",
mode="644",
)
need_restart |= incoming_header_cleanup.changed

submission_header_cleanup = files.put(
src=importlib.resources.files(__package__).joinpath(
"postfix/submission_header_cleanup"
),
Expand All @@ -284,7 +294,7 @@ def _configure_postfix(config: Config, debug: bool = False) -> bool:
group="root",
mode="644",
)
need_restart |= header_cleanup.changed
need_restart |= submission_header_cleanup.changed

# Login map that 1:1 maps email address to login.
login_map = files.put(
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1 change: 1 addition & 0 deletions cmdeploy/src/cmdeploy/postfix/incoming_header_cleanup
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Original file line number Diff line number Diff line change
@@ -0,0 +1 @@
/^DKIM-Signature:/ IGNORE
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Shouldn't this also scrub Authentication-Results then?

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@link2xt link2xt Mar 25, 2025 •
edited
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I don't see Authentication-Results, there is nothing that adds them. OpenDKIM is not configured to add them apparently.

Above the Content-Type header (the last one added by the client) I only see DKIM-Signature, Received and Return-Path. Maybe Received and Return-Path can be removed to reduce the amount of stored metadata further. These headers come from the receiving server.

1 change: 1 addition & 0 deletions cmdeploy/src/cmdeploy/postfix/master.cf.j2
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Expand Up @@ -52,6 +52,7 @@ smtps inet n - y - 5000 smtpd
#628 inet n - y - - qmqpd
pickup unix n - y 60 1 pickup
cleanup unix n - y - 0 cleanup
-o header_checks=regexp:/etc/postfix/incoming_header_cleanup
qmgr unix n - n 300 1 qmgr
#qmgr unix n - n 300 1 oqmgr
tlsmgr unix - - y 1000? 1 tlsmgr
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