Because VPOP3 uses a database for data storage, it will perform badly on a RAID 5 or RAID 6 array compared to simple disk or RAID 1 array. We recommend installing it on a RAID 1 or RAID10 array.
There are many articles on the Internet about why using a database on a RAID 5/6 array is a bad idea, so we won't repeat them here. Basically, small writes are incredibly slow.
(Some of these can be performed before installation as well, but we've put them here, because you can do them afterwards if you forgot beforehand.)
Make sure that any third party virus scanner is excluding the VPOP3\pgsql folder from its scans.
Consider disabling email scanning in any third party virus scanner. Desktop virus scanners are not designed to run on mail servers, so the email scanning part of a desktop virus scanner can be unreliable when run on a VPOP3 server.
Make sure that
write-back disk caching is disabled. (Unless you have a hardware RAID controller with a battery-backed or flash-backed write cache). If this is not done, then a power failure or forced shutdown of the PC may lead to database corruption
Make sure the vpop3postgres user in Windows is set to 'Password never expires'. The installer should do this during installation, but we have seen cases where it isn't set. If it isn't set then the database server may fail to start if your network security policy means that the password expires.