POP3 _SOMETIMES_ connection refused

explosive

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Dec 29, 2010
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181
Location
PL/EU
Hi,

I've strange problem with GMAIL:

GMAIL:
- settings/accounts/Check mail from other accounts (using POP3): added few external (from my servers) pop3 accounts

MY SERVER (those email accounts):
DA + CB 2.0 + Dovecot 2.1.15

Look: kVZWjen.png

Gmail sometimes give "Connection Error. Server returned error "Connection refused"" but as you see this is NOT permament error. Gmail fetch emails once per few times. So login/pass/server/port settings are OK.

In /var/log/maillog or /var/log/exim/* I have this positive connections from Gmail but NO any other, no "conection refused" from my side.

Anyone have some idea what may be wrong?

- no banned IP with CSF
- no banned IP in DirectAdmin BruteForce
 
Hello,

You should check /var/log/maillog for a clue. Probably you've got "too many connections" error. If this is the case, then you might need to tune /etc/dovecot.conf to allow more concurrent connections.
 
Hello,

You should check /var/log/maillog for a clue. Probably you've got "too many connections" error.

Nope. As wrote above nothing interesting in /var/log/messages. No "too many connections". If Gmail said "conecction refused" I don't have this entry in log. Only positive connections.
 
Did you check /var/log/maillog ? You might need to enable debugging in dovecot.conf for more detailed logging, if there is nothing in logs. If debugging does not help, then you might need to use iptables counters, or even tcpdump to make sure, that connections are not dropped by your server.
 
/var/log/maillog of course, sorry for typo. Yes, checked many times. I try dovecot debug now.
 
Dovecot debug = no entry when is "connection refused"

tcpdump = no entry when is "connection refused"

iptables = iptables -vL | grep 209 (gmail connects from 209.85.*) - no entries.

but how it's possible - one time it's ok, one time refused?!? I'm going crazy...

On other gmail account even can't connect with host every time (of course it's working from all over the world).
 
If it's not your DC who is dropping connections, then it might be an issue on Gmail's side.
 
Gmail side = I doubt it. Every other account works fine.

Moreover it's started when I've changed server. I've tested it with every other serwer in this DC and it's fine so it's MUST BE related with that particular server. BUT HOW?
 
tcpdump = no entry when is "connection refused"

If tcpdump shows no packets from Google at the very moment when you see error "connection refused, then it might mean that the packets does not reach your server. In this I'd guess you should either ask your DC or Google for further assistance.
 
I know this is an old thread, but after experiencing the same problem, find out if you are using IPv6 in your server. If so, make sure Dovecot is configured to listed in both IPv4 and IPv6, otherwise it will send connection refused as Dovecot is not listening in the first place.
 
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