1 Topic by starriol

  • starriol
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  • Posts: 7

Topic: Mail service unstable, sometimes clients can't connect

=== Required information ====
- iRedMail version: v0.8.5
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Linux/BSD distribution name and version: Debian 6
- Related log if you're reporting an issue:
====

Hi guys.
I've migrated from my hosting to a VPS with iRedMail our users, around 35.
I tested it on the weekend, it seemed to be fine.
But now clients are complaining they are receiving errors when trying to reach the mail server.
The strange thing is that I'm monitoring the server, making a TCP connection to IMAP, POP3 & SMTP, it has never failed, but my clients reported random downtimes of 10-20 minutes, after which the service restored itself without my intervention.

How can I troubleshoot this?
Which logs should I look into?
If the ports are OK, maybe it's a problem with the MySQL DB?

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2 Reply by ZhangHuangbin

  • ZhangHuangbin
  • ZhangHuangbin
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  • Registered: 2009-05-06
  • Posts: 31,091

Re: Mail service unstable, sometimes clients can't connect

Did you see your client's IP address blocked in iptables?
Fail2ban will monitor password failure, and block client IP address if there're 3 password failures in a short time.

3 Reply by drazenmd (edited by drazenmd 2013-11-01 21:07:55)

  • drazenmd
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  • Registered: 2013-11-01
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Re: Mail service unstable, sometimes clients can't connect

It's it  definitely problem with fail2ban, after couple of unattempted  logins it's blocking IP (default 600s), after that it's working normally. I had that problem too

4 Reply by starriol

  • starriol
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  • Registered: 2013-09-23
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Re: Mail service unstable, sometimes clients can't connect

Wow, thanks drazen, I'll look into that.