Alias expansion error

Help with Setup/Upgrade
1

I am using Zulip, a Slack-like messaging tool. It has the option of being able to respond to messages in the app via email. For that purpose it creates alias email adresses like this for each channel

zulip+6feab70a1cc46b8586feff156570a20e.show-sender@mybox.com

But when sending a message to that email from Thunderbird, I get the error

Sending of the message failed.

An error occurred while sending mail. The mail server responded: Alias expansion error. Please check the message and try again.

I guess, MIAB does not support that feature?

2

Actually it does support the + alias mechanism. But perhaps postfix chokes on the “.” or the “-” in the email? Check /var/log/mail.log to see if there are more details on the error there.

Update: duckduckgoing this a bit, it might not have anything to do with the default mailinabox installation. Did you have to do any changes to the configuration to get Zulip to work?

3

Thank you for the quick reply.

From mail.log:

Feb 18 12:18:14 box postfix/submission/smtpd[3352945]: connect from unknown[XXX.XXX.XXX.XXX]
Feb 18 12:18:15 box postfix/submission/smtpd[3352945]: Anonymous TLS connection established from unknown[XXX.XXX.XXX.XXX]: TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-si>
Feb 18 12:18:15 box postfix/submission/smtpd[3352945]: 604FD8007E: client=unknown[XXX.XXX.XXX.XXX], sasl_method=PLAIN, sasl_username=me@mybox.com
Feb 18 12:18:15 box postfix/cleanup[3352954]: warning: 604FD8007E: unreasonable virtual_alias_maps map nesting for zulip+6feab70a1cc46b8586feff156570a20e.show-sender@mybox.com -- message not accepted, try again later
Feb 18 12:18:15 box postfix/submission/smtpd[3352945]: disconnect from unknown[XXX.XXX.XXX.XXX] ehlo=1 auth=1 mail=1 rcpt=1 data=0/1 commands=4/5

There is an option in Zulip to have the address without the .show-sender part, which I tried, but the result was the same.

I did do another search as well, but could not find anything that seemed like a hit.

IIRC, I did not have to do any modifications on MIAB (apart from making a user). I followed the last section of this:

https://zulip.readthedocs.io/en/stable/production/email-gateway.html

4

I tried it on my box by sending mail to user+6feab70a1cc46b8586feff156570a20e.show-sender@mybox.com which works without a problem.
I wonder if the zulip address is a user/mailbox or an alias? Perhaps there are already aliases defined on your box that interfere? E.g. a domain alias or a aliases that refer to each other?

1 Like
5

Indeed! zulip@mybox.com was an alias of noreply@mybox.com and vice-versa. I do not remember why that was there. It may have been necessary during the transition of one messaging app to another.

It works fine now. Thank you for your help!

6

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