I have a Samsung S3 Mini. When I delete emails from the phone, I find that they have gone into the trash folder on virgin media so they are not downloading to my puter or laptop - which I want them to. I've checked setting on both phone and at Virgin Media but cannot see how to stop this.
Really? With the workflow described in the OP I would have suggested POP3.
Set the phone to "Leave messages on server" and set the computer to "Remove from server after download". Anything deleted from the handset is only deleted locally and can still be downloaded by the PC.
POP3 has the advantage that an email is only downloaded once, no matter how often it's looked at. The disadvantage is that it downloads the whole message rather than just the headers. Considering mobile data limits, either of these might affect your choice depending on the typical makeup of your incoming emails and whether you need to actually read them before deleting.