Haunted Emails...

[Sterillium]

When I send an email (through Outlook Email) the moment I press send, the email vanishes, and immediately two drafts then appear in my draft folder; one which is to the same recipient but is blank, and a second which is also to the same recipient and is the email I just tried to send... No idea why this is happening, it seems to happen with some recipients and not others - is it a setting I have buggered up?