This issue seems to be specific to a user rather than a PC. It started happening when upgrading their PC originally to Office 2007 (they were using Outlook Express before,) and joining them on the domain. I have tried them on a different PC and the problem still occurs.
Basically, when outlook is first opened it redownloads the messages on the pop3 server. Once open it will not receive them again until Outlook is restarted. I could change the settings to delete emails on the server, however this is only a mask to hide the error instead of being the cause.
I have tried disabling the virus scanner temporarily, but no joy.
Can anyone tell me what part is responsible for deciding which emails are required?
While we’re at it… any suggestions on a program for deleting repeat emails? There are thousands of them now.