Imapsync problems

Luricaun

Hello community,

I noticed a weird problem with the imapsync feature which I am using to collect mails from various sources on my mailcow. Here is a part of the log entries I get when trying to sync mails from my classic hosted mailcow system.

Host1: connecting and login on host1 [hosted.mailcow.de] port [143] with user [xxx@xxxx.xxx] Host1 failure: can not open imap connection on host1 [hosted.mailcow.de] with user [xxx@xxxx.xxx]: Unable to connect to hosted.mailcow.de: Invalid argument

[…]

Err 1/1: Host1 failure: can not open imap connection on host1 [hosted.mailcow.de] with user [xxx@xxxx.xxx]: Unable to connect to hosted.mailcow.de: Invalid argument The most frequent error is ERR_CONNECTION_FAILURE_HOST1 Exiting with return value 101 (EXIT_CONNECTION_FAILURE_HOST1) 1/50 nb_errors/max_errors PID 3184 Disconnecting from host2 localhost user2 yyyyy@yyyyy.yyy*dogt75kz1fmd25c6@mailcow.local

I have no idea what the invalid argument could be. I added screenshots of my settings for one of those syncs.

Any idea or help would be appreciated.

Thanks, Luricaun.

tbrummell

Don’t you need to use port 993 if using encryption?

Luricaun

tbrummell Thank you for the hint. Unfortunately I have already tried this option as well. I haven’t changed a thing in the configuration and it did work a couple of days ago so I am still baffled why it stopped working.

Host1: connecting and login on host1 [hosted.mailcow.de] port [993] with user [xxx@xxxxx.xxx] Host1 failure: can not open imap connection on host1 [hosted.mailcow.de] with user [xxx@xxxxx.xxx]: Unable to connect to hosted.mailcow.de: Invalid argument

Luricaun

I just want to let you know that I found the solution (with the Telegram support group) for my problem.

It was a DNS problem. Here is a quick sum up.

I am using a pi-hole as a DNS server locally (internally) and I block pretty much any other DNS traffic except to pi-hole from internal networks. Only pi-hole is allowed to do external DNS requests. It seems I had to enable external DNS requests for the mail system as well nowadays. Once I did allowed all DNS traffic from my internal mailcow it worked again right away.

So in case someone stumble upon a behaviour like this, maybe DNS is one way to look at it.

So this case is closed.