Right, I've had problems now with 3 accounts. The old thread where I was figuring stuff out as it happened is here The rundown: First client has problem with mail 'sticking' at x of x, say 4 of 10 where message 4 will not download. Logging onto the server and moving/removing the message allows the rest of the messages through fine. The problem occurs when collecting mail via POP3 and POP3/SSL but not via IMAP. I do not want to start encouraging users to leave mail on the server however.. I have had the problem 3 times at 3 different sites. The first site was fixed by doing a firmware upgrade to the router (a Netgear). The second site had the same router but a firmware upgrade didn't fix it. Neither did replacing the router for a different one (Speedtouch). I was extremely busy (ie a month and a half with no other staff helping) so just switched them to IMAP. When I got round to re-investigating, the problem had vanished. The third site is a new account on the server, this one has a Cisco router so I think we can safely say it is not a router issue. All 3 sites use the same ISP (BT Broadband). The actual problem is that the client connects, issues all its commands down to the RETR and when the server sends the TCP ACK to the packet with the RETR that ACK never gets to the client. My server is running FreeBSD 6.2 so I was wondering if there is any way to replace the cpanel courier with something else. If the same problem occurs with different software then I know the issue has to be on the network somewhere. It is doing my nut in completely, and understandably the end user is getting annoyed at having their mail broken several times a day..