Usually this is caused by anti virus program being slow in scanning large messages resulting in a time out so the message comes again next time you get mail. Try it without mail scanning and see if there is an issue still.

My VERY slow server has been abandoned and the problem went away with it.

Thanks Matt

just how slow Kenny? Those sorts of errors and cures are common. and what your offering is basically new information or a new insight into an old problem.

How slow, incredibly slow. Speedtest.com reports 0.2 Mbps and even less at times. In early morning (5 am) it can get up to ~2 Mbps sometimes - not always. Frontier's own speedtest.frontier.com times out before it can get a reading.

So this is not your own server, but Fronteirs? This forum has been full of people this week complaining about them... Apparently they are advising them there is something wrong with Thunderbird.