VPOP3 Is Responding Slowly

If VPOP3 is responding slowly to users there are several common causes:

The VPOP3 server disk may be badly fragmented. Defragment the server disk(s). Note that sometimes the Windows defragmenter will say that the disk doesn't need defragmenting even if it does, so it is best to do it anyway. Also, there is a better free defragmenter available called MyDefrag.

The server disk may have a problem - check the disk. If the disk is starting to fail, then it will result in disk accesses having to be retried, which will slow things down.

Unnecessary server logging may be turned on. Go to Settings → Diagnostics → Session Logs and make sure that all session logging is disabled. This should only be enabled if technical support ask you to enable it.

Antivirus software, especially email aware antivirus software may slow things down. Try disabling any third party email virus scanning, and try excluding the VPOP3 installation directory and subdirectories from any real-time/on-access virus scanning to see if that makes any difference.

Try a different email client, such as Outlook Express, Windows Live Mail, Mozilla Thunderbird to see if the problem is email client related.

Try running an email client on the VPOP3 computer itself. If this is quick, then that suggests a network issue or something on the user's PC. Note that some network problems will cause network traffic to be retried, rather than just failing outright, so will appear as a slowdown.

If the problem is with incoming mail, or sending mail, then check to see if the WHITELIST.TXT file in the VPOP3 directory is excessively large. If this is over about 5-10MB it may have lots of unwanted entries in it, slowing down any spamfilter whitelist checks. In this case, stop VPOP3, rename the WHITELIST.TXT file to WHITELIST.OLD.TXT and restart VPOP3 to see if that solves the problem.

If VPOP3 is installed on Windows Home Server (WHS), check that it is not installed in the 'pooled storage' area (drive D:). VPOP3 does not work reliably if installed on this drive. It either needs to be installed on drive C:, or on another drive which has not been added to the storage pool.