How are you receiving your mail? If it is by POP3 through MercuryD you could start by increasing the download timeout considerably. To find out exactly what is stopping transfer switch on session logging for the next download session (but please remember to switch it off again).

/Rolf

Everytime i check my host for new mail, i receive the same mail over and over again, even though they only been sent to me once (I know, cause I'm the one sending them). What can I do to stop this? It's quite annoying.