Mar 27, 2026 - For details about updated CVE-2025-53521 (BIG-IP APM vulnerability), refer to K000156741.

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Dmetcalfe_13626's avatar
Dmetcalfe_13626
Icon for Nimbostratus rankNimbostratus
Nov 27, 2013

How to create a VS to load balance POP3 and IMAP

I have 2 5000 series loadbalancers with LTM. Is there a simple way to load balance POP3 and IMAP mail servers. Our customer facing mail does SMTP (which I have working), POP3 and IMAP. I can't figure out how to get POP3 or IMAP to work. I'm very new at this, so thus far all I've done is create a VS for each with the ports 110 for POP3 and 143 for IMAP, but I have no idea what else I should be doing. Do I have to collect and pass the auth information? Clueless.

 

design

3 Replies

  • rob_carr's avatar
    rob_carr
    Icon for Cirrocumulus rankCirrocumulus
    Nov 27, 2013

    If you are load-balancing traffic to servers that require authentication, and your back-end servers aren't in a cluster (where the servers share session state information), then more than likely you will need to enable persistence.

     

    http://support.f5.com/kb/en-us/solutions/public/13000/400/sol13478.html

     

    • IheartF5_45022's avatar
      IheartF5_45022
      Icon for Nacreous rankNacreous
      Nov 28, 2013
      Let me elaborate - you statement "If I telnet directly to the virtual server from the F5 on port 110 I can send and receive mail manually, but for some reason when I put the virtual server address into a client with port 110 I cannot retrieve mail??? " smells like a SNAT issue. Try configuring SNAT Automap on your virtual and see if that fixes the issue.