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Thread: IMAP - Dropping connection (max connections exceeded)

  1. #1
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    Default IMAP - Dropping connection (max connections exceeded)

    Hello,

    I'm experiencing some problems with the IMAP connections. No matter, that the max threads are set up to 10000 once all of the employees are in the office (around 150 people) at some point the imap server is starting to drop some of the connections. All necessary settings are made in order Zimbra to serve our office, but still we are having issue. We are using Thunderbird on most of the workstations, if this have anything related to the issue. Thanks in advance

    ps. Here is some greps from the mailbox.log also the configuration for IMAP is 10000 threads + 250 connections per IP
    ----
    2012-10-15 10:06:11,120 WARN [ImapServer-11] [] imap - Dropping connection (max connections exceeded)
    2012-10-15 10:06:13,739 WARN [ImapServer-20] [] imap - Dropping connection (max connections exceeded)
    ----

    2012-10-15 10:11:33,020 WARN [ImapServer-3] [ip=XXX;oip=192.168.1.2;via=192.168.1.2(nginx/1.2.0-zimbra);ua=Zimbra/8.0.0_GA_5434;] imap - too many IMAP requests from original remote ip 192.168.1.2 dropping connection
    2012-10-15 10:11:33,078 WARN [ImapServer-5] [ip=XXX;oip=192.168.1.2;via=192.168.1.2(nginx/1.2.0-zimbra);ua=Zimbra/8.0.0_GA_5434;] imap - too many IMAP requests from original remote ip 192.168.1.2 dropping connection
    2012-10-15 10:11:33,136 WARN [ImapServer-2] [ip=XXX;oip=192.168.1.2;via=192.168.1.2(nginx/1.2.0-zimbra);ua=Zimbra/8.0.0_GA_5434;] imap - too many IMAP requests from original remote ip 192.168.1.2 dropping connection
    2012-10-15 10:11:33,191 WARN [ImapServer-3] [ip=XXX;oip=192.168.1.2;via=192.168.1.2(nginx/1.2.0-zimbra);ua=Zimbra/8.0.0_GA_5434;] imap - too many IMAP requests from original remote ip 192.168.1.2 dropping connection

  2. #2
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    Default

    We are getting the same errors.

  3. #3
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    We really need some information how to solve this, it seems that Zimbra is bypassing any configuration made to the imap threads.

    Also I've tried to set the maximum imap threads from the Thunderbird's configuration to 1, but nothing really changed.
    ANY further information will be much appreciated!!!

  4. #4
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    I'm experiencing the same errors, and will post any new findings here to help others.

  5. #5
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    I upgraded to ZCS 8 on Saturday, and all seemed ok. Now that my users are back and hitting the server, I'm getting this error as well. Most accounts are not receiving any inbox information.

    They can log in via the web interface and all is ok; they just cannot get mail to their mail clients (Apple Mail, Thunderbird, Outlook, etc).

    -=edit=-

    After reinstalling the GoDaddy SSL cert, and then resetting the IMAP connection from 500 to 300 to 700, now it seems to be ok.
    Last edited by n4bbq; 11-12-2012 at 08:31 AM.

  6. #6
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    Update :

    None of the above fixed it.

    I re-uploaded the GoDaddy certs and thought all was well, but here we are about an hour later and I'm seeing hundreds of log entries in mailbox.log concerning "max connections exceeded" again.

    Code:
    2012-11-12 12:04:57,899 WARN  [ImapSSLServer-10] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:04:57,932 WARN  [ImapSSLServer-5] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:04:58,254 WARN  [ImapSSLServer-5] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:04:58,263 WARN  [ImapSSLServer-11] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:04:58,268 WARN  [ImapSSLServer-1] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:04:58,278 WARN  [ImapSSLServer-8] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:04:58,286 WARN  [ImapSSLServer-10] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:04:58,290 WARN  [ImapSSLServer-9] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:05:00,005 WARN  [ImapSSLServer-1] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:05:00,030 WARN  [ImapSSLServer-10] [] imap - Dropping connection (max connections exceeded)
    2012-11-12 12:05:00,060 WARN  [ImapSSLServer-9] [] imap - Dropping connection (max connections exceeded)
    All from the SSL area. I must not be getting the SSL stuff uploaded correctly although it says its correct from the admin console. Time to dig into the forums a bit.

    With SSL off, my IMAP account works fine (Apple Mail).

  7. #7
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    Ok back again.

    It looks like all is well. When I upgraded to 8.0 this weekend, the server reset it's "zimbraImapMaxConnections" back to 200. I increased that back up to 500 and haven't had a problem since then.

    Read it
    Code:
    zmprov gs my-server.com zimbraImapMaxConnections
    Set it
    Code:
    zmprov ms my-server.com zimbraImapMaxConnections 500
    Plus you might want to check the setting for "zimbraImapNumThreads" as well.
    Last edited by n4bbq; 11-12-2012 at 11:32 AM.

  8. #8
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    thank you for the hint.
    same problem was here after upgrading to network edition 8.0.1 - limit was 200....

  9. #9
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    Also, try to set
    Code:
    zmlocalconfig -e imap_throttle_command_limit=500
    I am not quit sure about amount "500", how it would impact IMAP or Zimbra stability. But This worked for me - I am not getting "dropping connectins" when running imapsync locally from server.

    http://www.zimbra.com/forums/adminis...tml#post253107
    Release 8.0.1.GA.5438.UBUNTU12.64 UBUNTU12_64 FOSS edition.

  10. #10
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    Quote Originally Posted by arnisraido View Post
    Also, try to set
    Code:
    zmlocalconfig -e imap_throttle_command_limit=500
    I am not quit sure about amount "500", how it would impact IMAP or Zimbra stability. But This worked for me - I am not getting "dropping connectins" when running imapsync locally from server.

    http://www.zimbra.com/forums/adminis...tml#post253107
    There is always the case that you are in a migration phase and during that imap is usually used with the admin account just to hijack the zimbra mailbox and sync all users mail.
    In that case, there is a specific configuration option that you should check

    Code:
    zmprov mfc zimbraAdminImapImportNumThreads 20000
    {just for the migration phase} Do not forget to put it back to 50. 20000 is more than too much.

    Nikos
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    Zaharioudakis Nikos, RHC{A,DS,E,VA,X,I}, VCP(4,5},VCI, Mentor VCI, Zimbra Instructor
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    +30 694 720 40 63
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