Thanks to all those who contributed to this really helpful thread. I was experiencing the same issue with received emails being automatically deleted. I have made the adjustments to the "synchronisation" options. Hopefully this will work.
This leads me to another question about deleting emails. When invoking the "delete" option through the menu on the BB, 3 options are presented - "mailbox and handheld"; "handheld"; "cancel". The reference to the mailbox, does this relate to the email account (through my ISP) that I have configured the BB to be linked to?
Many thanks in advance.....