Inbound Mail Non-Functional

Maintenance
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My MiaB instance has been hosted at DigitalOcean for the past few years with no trouble. It looks like all inbound mail to my instance began to silently fail a few weeks back.

Testing today shows all green v56 on my status page and emails sent from my domain to a gmail account succeed. When I send mail to my domain from gmail, it just never seems to show up. The sender gmail end doesn’t get any failures I can see. Attempting a “telnet DOMAIN 25” fails from my home network out, while a “telnet DOMAIN 587” succeeds.

Does this sound like something suddenly blocking inbound port 25 at the DigitalOcean end? Any recommendations here?

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Does you home network connect on port 25 to Google? It is common for residential ISPs to block port 25.

Is there anything in /var/log/mail.log when Google connected to MiaB?

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I did get access to a different machine, not on my local network. Telnet on 25 to my MiaB instance on digitalocean did work from that machine, so no problem there it seems.

It did a few more tests and found a hopefully useful error in the mail.log. I use a significant number of mailbox aliases that point to this particular mailbox. Unsure what it’s complaining about though. Mail sent to and from other mailboxes does succeed.

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You are only adding aliases through the dashboard?

Have you changed anything else on the system?

Approximately how many aliases is a significant number?

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Only aliases from the dashboard, no other changes. Somewhere on the order of 200 aliases (I know). I did seem to figure it out though.

I double checked a few recent alias additions. Normally it’s NEW_EMAIL@DOMAIN as alias with “forwards to” set as my common mailbox, say xyz@domain. On one entry I had reversed those fields somehow. So it was trying to forward mail thinking that common mailbox xyz@domain was itself an alias, hence the log error.

This closed github issue entry gave me the idea. Thanks for prompting me in the right direction @openletter ! Alisas · Issue #186 · mail-in-a-box/mailinabox · GitHub

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With some additional testing, more specifically my email alias misconfiguration which gave the “unreasonable virtual_alias_maps map nesting” mail.log error was trying to route mail to a mailbox which did not exist, while the configured alias name conflicted with an existing mailbox.

For example, alias@domain.com configured to forward to doesNotExist@domain.com will send back a “could not deliver” message to the sender. But my above scenario silently fails for both sender and receiver. I’ll work this one as an issue on github [Feature Request] Detect Misconfigured Aliases · Issue #2112 · mail-in-a-box/mailinabox · GitHub

1 Like
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Yep. As someone with hundreds of aliases I recognize this problem; it happened to me once. It would be nice to have a pulldown menu with valid mailboxes in the 'Forwards To" field so the chance of entering a non-existent address would be lower.

But then, that would be probably unworkable for anyone with a lot of mailboxes in their MIAB as the list then would be long. So I’ll keep double checking every time I enter an alias :slight_smile:

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