Excessive IMAP CLOSE_WAIT sessions

Discussion in 'Server Operation' started by iyeat, May 1, 2008.

  1. iyeat

    iyeat New Member

    Hi all,

    I've implemented a mail server using Fedora 8 and the Virtual Users And Domains With Postfix, Courier And MySQL (Fedora 8) Tutorial. It's worked GREAT until the last week or so.

    It seems that courier-imap is starting to reach its Max Number of connections very quickly after starting up. Sometimes it only takes 10 minutes for the server to stop responding.

    When the server stops responding, there appear to be an obscene number of CLOSE_WAITs for courier-imap when running a netstat -tap on the server.

    I originally thought that the issue was that I had the MAXDAEMONS value in the courier-imap imapd configuration file too low. It started at 30, ten rose to 50, 75, 100, and 200... the problem only getting worse as I raised the value.

    Does anyone have an idea of what else I can do to troubleshoot this issue? My users are complaining of frequently not being able to access the imap server several times per day. Restarting courier-imap always fixes the problem, but it comes back very quickly.

    Thank you for any help! I just restarted the server, but when this issue presents itself again, I'll post an output of top, as well as netstat.


  2. falko

    falko Super Moderator ISPConfig Developer

    Can you post your Courier configuration files?
  3. iyeat

    iyeat New Member

    I'm not sure which files you need specifically.. I've enclosed my imapd and imapd-ssl files for your reference.



    Attached Files:

  4. falko

    falko Super Moderator ISPConfig Developer

  5. iyeat

    iyeat New Member

    I've read through all of these before...

    I just doubled my maxperip setting to 80 and my maxdaemons setting to 400. Hopefully that will help. We have only IMAP users, and learning about an issue with Outlook IMAP leaving connections open is not good :(

    Does anyone else have thoughts?

  6. iyeat

    iyeat New Member

    Just had this happen again...

    Here is my TOP output before and after...


Share This Page