New
#31
There are basically two ways to scan email - as it's downloaded, and as it's opened.
Scanning while downloading often causes problems - resulting in hung mail clients and error messages.
Whenever you open an email, the AV gets another crack at it at that point anyhow - and this may be the best point, as the AV may have been updated to deal with the 'bad' content since the email was downloaded (and you don't often open many emails at the same time!).
When you say 'won't delete' - what error message do you get? Is this from the Rescue AV?