I have been using eM client for years but all of a sudden I am getting the error “unsupported mail address” on one of my accounts. The other account continues to work fine. The email with the error is @msn.com. What is going on? How do I fix this?
where do you get this message? When sending email or as feedback from a server?
Everytime the account tries to refresh I get the error. I cannot refresh the account at all. I have deleted the account and reinstalled it and I still get the same error.
Look to see if there is an email sitting in your outbox. It appears that maybe the address on the email is incorrect and cannot be parsed by eM Client. Deleting this email should clear the problem. Note that the outbox is a local folder. To make sure you can see it, in the folder pane, right-click on Smart Folders, chose Display and check Outbox.
The outbox is empty. So are all the other folders because I deleted the account and tried to reinstall it. It will not download any emails at all. I have attached the error log if that helps. 
Any more suggestions?