I am getting the same, but it is 100s of the same 2 sent emails. I also can't send or recieve emails in Mail. I am recieving them on iCloud webmail but can't send from there either. Here is what has happened:
1. Yesterday could not view 2 sent emails.
2. Today they started coming in as unread 'recovered' emails, and I am getting them 100s of times over
3. Since this morning I haven't been able to send or recieve emails in Mail, although incoming ones are on server. Can't send any from iCloud.
What's going on?