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The server has reached its limit for processing requests from your host.n451

Discussion in 'E-mail Discussions' started by MarcelB, Nov 12, 2008.

  1. MarcelB

    MarcelB Well-Known Member

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    I keep having a large mail queue on server1 trying to send it to server2. Both servers are mine and IP's are allowed in the firewall.

    When I force email on server1 to be delivered through ConfigServer Mail Queues there is the following error:
    451-The server has reached its limit for processing requests from your host.n451 Please try again later.

    Even a reboot of server2 didn't solve the problem.

    What could be the problem here ?
     
    #1 MarcelB, Nov 12, 2008
  2. nickp666

    nickp666 Well-Known Member

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    its probably exim's ratelimiting, add your servers IP's to the whitelist in WHM > Exim Configuration

    Also check the value of the 'Maximum Emails a Domain Can Send In 1 Hour' value in WHM > Tweak Settings
     
    #2 nickp666, Nov 13, 2008
    Last edited: Nov 13, 2008
  3. mikelegg

    mikelegg Well-Known Member

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    I just started having this problem with one of my servers rejecting mail from my backup MX server - despite the fact that the backup server is included in WHM >> Exim Configuration Editor >> Exim Backup Mail Hosts.

    The server was just down for some scheduled maintenance and now a heap of our customers mail is stuck in the secondary MX queue - unable to be accepted by the main server.
     
    #3 mikelegg, Feb 25, 2010
  4. mikelegg

    mikelegg Well-Known Member

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    I've found a temporary solution.

    I've turned off the "Ratelimit: incoming SMTP connections that do not send QUIT, have recently matched an RBL, or have attacked the server." option.

    The mail is being delivered now.

    So adding a backup server to /etc/backupmxhosts doesn't actually whitelist it.

    I'll need to find a way of turning this option back on without blocking the sMX server again.
     
    #4 mikelegg, Feb 25, 2010
  5. nitaish

    nitaish Well-Known Member
    PartnerNOC

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    Here is the option

    Whitelist: Trusted Mail Hosts/IP Blocks (bypass all SMTP time checks except recipient verification)
     
    #5 nitaish, Mar 31, 2010
  6. aarondwyer

    aarondwyer Well-Known Member

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    I had this rate limiting issue on my backup MX server as well.

    I simply added it to /etc/backupmxhosts and it worked.

    However in my Exim I don't have the ability to tick the option for ...

    Whitelist: Backup Mail Hosts (bypass all SMTP ratelimits).

    I don't know why

    Aaron
     
    #6 aarondwyer, Apr 13, 2010
  7. patriciaguedes

    patriciaguedes Registered

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    I found this same problem and did as below and it worked:
    You can change the max smtp connection in /etc/exim.conf using below parameter :

    smtp_accept_max = VALUE

    The VALUE is the number you need to set according to your needs. You can experiment by increasing it a bit from its current value and see if it fulfills your requirement else you can increase it further until it works for you.
     
    #7 patriciaguedes, May 2, 2011
  8. cPanelTristan

    cPanelTristan Quality Assurance Analyst
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    I did want to note that smtp_accept_max is the maximum number of simultaneous SMTP connections on the machine for anyone who is not familiar with this setting. The default for cPanel machines in /etc/exim.conf is 100.

    The proper method to revise this value would be in WHM > Exim Configuration Editor > Advanced Editor area. In the topmost box, if you input the value and click the "Save" button:

    Code:
    smtp_accept_max = 200
    For example, it would change the value from "smtp_accept_max = 100" to the new 200 value. Any entries put at that topmost box for fields immediately below are removed and re-added with your new configuration setting.

    If you manually edit /etc/exim.conf instead under cPanel, then whenever /scripts/eximup --force is processed, the value you've changed will be removed and the default set again. Thus, you would want to use WHM > Exim Configuration Editor > Advanced Editor to change the value.

    To read about smtp_accept_max directive for exim, please review the following documentation from the exim site:

    Exim Specification - Main configuration
     
    #8 cPanelTristan, May 2, 2011
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