help proving slow/failing IMAP connection
(I thought I posted this yesterday but I can't find it anywhere).
I am posting on behalf of a colleague who has Virgin cable broadband at home. He has a 20mb service and a bunch of recent speed tests show he is getting an average of 19.5mb. All good.
His home PC is Windows XP, which is wired into his Virgin supplied router/modem. He uses Outlook Express to connect via IMAP to a mailbox hosted at a 3rd party ISP (which is run by a friend of his). All this was working fine until a few weeks ago. Now Outlook downloads emails extremely slowly. It barely manages text-only emails, anything with an attachment simply fails. Outlook times out and prompts the user to either wait or cancel. Sending email is quick however.
The things I have test for, so far, are...
Outlook Express - I installed Mozilla Thunderbird and configured the account on there. Same problem. Still slow to download.
Mailbox - I thought it might be his mailbox. So configured an additional account in Outlook Express to connect to a Gmail mailbox over IMAP. This downloaded emails quickly
Profile - There are two separate user profiles on his computer (him + wife). They have separate mailboxes with the same 3rd party ISP. Both have symptoms of slow/timing out email downloads
Ports - The ISP supports IMAP (143) TLS (993) - I have tried both and the symptoms are the same. The friend at the ISP also temporarily allowed connections on port 80, but again it was slow/failing to download emails.
Anti-Virus - The computer is running AVG free (version 8), which I believe does not have any Outlook Express integration. I also disabled real-time protection to see if this was affecting downloading. Same problems.
Alternate PC - To rule out the PC, I gave the user a work laptop to take home. I configured Outlook Express with his account and tested it in the office. It was quick to download email. He took this home and plugged this into a spare port on the router and I tested it remotely. It was slow to download.
Network - From this work laptop I VPN'd back into the office and tested again. It was quick. I disconnected the VPN and it was slow again.
What else is there left to test/prove? Any help/advice greatly appreciated.