Email woes


I'm new to the world of Android phones (HTC Desire) and to this forum and I've got a knotty problem that I'd really appreciate some help with.

Ive set up my Desire to download email from my email accounts using the standard mail ap. The trouble I'm having is that the emails disappear from my inbox and sent items seemingly at random. At first, it was deleting emails wholesale after 2 or 3 days but now it's much worse.

For example, the day before yesterday, I received an email which I opened and read and then went back to the mailbox. The mailbox refreshed and the email vanished. This morning, a new email disappeared before my eyes before I even had a chance to open it when the mailbox refreshed.

I've tried setting the sync option variously to "all emails" and "200 messages" but that doesn't seem to have helped, and I can't find any other settings which control how long emails are kept for. I've also tried ticking the box so that it prompts before deleting, but that hasn't helped either.

The incoming emails are still on the mail server, so I can still access them through webmail if I need to, but the sent items are gone for good unless I forward them to another address and pick them up on my PC (i.e. the disappearing emails don't get moved to Trash).

I'm running the official Froyo 2.2 version of Android, but the problem was the same under 2.1. I use the Virgin Media (UK) email service (blueyonder), which is based on gmail. (Because of that, I did try the Google Mail ap and although it would let me set up the accounts and sync contacts, it always failed when it tried to sync mail. Hence, I'm stuck with the Android ap.)

How can I stop my emails from disappearing? :(