Hi everyone, I'm running Mailcow using the standard docker-compose setup. I'm currently trying to solve an issue with autoresponder (vacation) messages generated by Dovecot Sieve. These messages are not going through Postfix and thus are not DKIM-signed or SPF/DMARC-compliant. This causes problems with delivery, especially to Gmail and other strict providers. I understand that Dovecot sends these messages internally (bypassing the MTA), and this setup makes sense in a single-container environment. However, in Mailcow, Postfix and Dovecot run in separate containers. Using sendmail from within the Dovecot container doesn't work, since Postfix is not available locally. My goal: Make sure that autoresponder messages from Dovecot go through Postfix like any other outbound email, so that DKIM signing and SPF alignment are applied. Has anyone solved this in Mailcow, or is there a recommended way to forward these internal messages to Postfix from Dovecot's container? Any tips on how to properly configure this in the Mailcow context? @"DerLinkman"#1496 ? Thanks in advance!

Hello, I believe you are fundamentally wrong. Dovecot does not communicate to remote server as Gmail other than in client-server way, meaning IMAP/POP. So if something is sending vacation responses to Gmail it is Postfix. Edit: ok I try this Sogo -> Settings -> Mail -> Vacation -> Enable vacation auto reply Message in Gmail is just fine SPF pass whit correct IP, DKIM pass with correct domain, DMARC is PASS Also after inspecting my MC logs, `Jun 17 10:30:44 b98b56336a9a postfix/smtp[10792]: 5B687106607: to=, relay=gmail-smtp-in.l.google.com[108.177.127.27]:25, delay=1.1, delays=0.51/0.05/0.12/0.45, dsn=2.0.0, status=sent (250 2.0.0 OK 1750149044 a640c23a62f3a-adec897e2bfsi740398166b.696 - gsmtp)` It's Postfix who is sending vacation notification

in Sogo, there you can specify if the vacation response is done by a filter ("always send vacation response"). Maybe this is the reason why it is bypassing postfix.

My vacation: settings [upl-image-preview uuid=be61ff95-a235-4bad-8b4f-c5adb452e9dc url=https://community.mailcow.email/assets/files/2025-06-17/1750150028-725909-screenshot-from-2025-06-17-10-45-38.png alt={TEXT?}]

Thank you for your reply! In our case, we have disabled SOGo completely, and we are configuring Sieve filters directly via the Mailcow admin panel, not through SOGo’s interface. Our autoresponder logic is handled entirely by Dovecot with Sieve, and from our observations, the messages generated this way do not seem to be passing through Postfix, which results in missing DKIM signatures and failed SPF/DMARC alignment — leading to Gmail rejecting them or marking them as suspicious. We understand your setup works fine with SOGo-enabled vacation replies, but since we’re using only raw Sieve (without SOGo), perhaps the message delivery path is different in this case? Any idea how to ensure Sieve-generated vacation messages go through Postfix when SOGo is not in use?

Can you provide part of sieve settings related to vacation?

Right: [upl-image-preview uuid=328fc32e-0e89-4619-9591-6215dfaf58f7 url=https://community.mailcow.email/assets/files/2025-06-17/1750162621-747061-image.png alt={TEXT?}]

So that is a rule that sends for **every** mail address an autoresponder? What kind of sense does that make? Postfix typically chooses the relay based on the sender domain or the envelope sender (MAIL FROM). If the Sieve vacation response uses a local address, Postfix may bypass your intended relay host for external domains

I thought something to c&p to test it and observer behavior on my server, also this is in MC where exactly? Rspamd maps?

This is our standard vacation/autoresponder setup, used to notify senders during a user's absence. It’s not configured to respond to every message globally, but rather per mailbox. Each user has their own filter enabled only when needed. Is there a better recommended way to handle this in Mailcow without SOGo? We’re not using SOGo – all filters are configured in the Mailcow admin panel, under: Configuration > Mailboxes > Filters Here's a copy-paste version of the Sieve script we’re using for vacation responses: ``` require ["fileinto", "vacation", "copy"]; # Move spam to spam folder if header :contains "X-Spam-Flag" "YES" { fileinto "spam"; # Stop here so that we do not reply on spams stop; } vacation # Reply at most once a day to a same sender #:days 1 :subject "Out of Office Reply" :addresses ["*"] :mime "MIME-Version: 1.0 Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 7bit Please be informed that I am out of the office until June 15, without access to email. I will respond to all messages upon my return. For urgent matters, please send a message to: support@example.com "; ```

Just test it. Added your filter in `Configuration > Mailboxes > Filters` as `prefilter`. Must slightly change the script due to linting HTML part (missing \ on body and link). But important is that my MC did it right. From header of vacation responder ``` Delivered-To: *@gmail.com Received: by 2002:a05:6359:4292:b0:1ee:2ab7:e0e7 ARC-Seal: .... ARC-Message-Signature: ..... ARC-Authentication-Results: i=1; mx.google.com; dkim=pass .... spf=pass .... dmarc=pass .... Received: from my-server by mx.google.com with .... Received-SPF: pass .... Authentication-Results: mx.google.com; dkim=pass .... spf=pass ... dmarc=pass ... Received: from sieve (sieve)... DKIM-Signature: .... Authentication-Results: my-server; none X-Sieve: Pigeonhole Sieve 0.5.21.1 (49005e73) Subject: Out of Office Reply ..... ``` Did you made some "unofficial" configuration other than disabling SoGo?

Send Dovecot Sieve autoresponder emails through Postfix (separate container)

zx1100e1

What’s the strategy to get a vacation response for bcc type emails?

Use case - family member belongs to a group that fat fingered the correct email address. Attempts to get it corrected have failed. Because of a catchall, the message still arrives. Rather than do a hard bounce, message receipt is still important, but we do want to fix the behavior so the other end corrects the email address.

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