This is a bit of guesswork but it's based on using an email service where the domain name in email address is not the same as the domain name used by the sending server :
(1) Check whethe the user name is correctly completed. With most email accounts, only the part before the '@' is used as the username. (In your example, the username would be 'me'). However, where various domain names are in use, it's common to use the full email address as the username. (In your example, the username would be
[email protected].).
(2) Where the domain name of the email address is not the same as the domain name used by the server, it's common to require 'authentication' for outgoing mail. Go to Tools > Accounts > Mail. If you've got more than one email account, click on it to highlight it. Click Properties > Servers. Click to place a tick alongside 'My server requires authentication'. Click 'Apply' and 'Ok'.
Chris