Outgoing email no longer works

Question

Haven't change my email set-up in years, but suddenly getting error messages saying "cannot send message using server smtp.mac.com:
It asks me to select another server. Still receiving emails, just can't send any out. Don't understand what happened.

Answer 1

Hello,
Surprised you're still getting eMails, MobileMe/dot Mac servers were killed about July 1st in favor of iCloud.
Do not delete the old account yet. sign up for an iCloud account if you haven't.
I understand .mac mail will still come through. Do not delete the old account yet.
You cannot use .mac or MobileMe as type of Account, you have to choose IMAP when setting up, otherwise Mail is hard coded to change imap.mail.me.com to mail.me.com & smtp.mail.me.com to smtp.me.com, no matter what you try to enter.
iCloud Mail setup, do not choose .mac or MobileMe as type, but choose IMAP...
On second step where it asks "Description", it has to be a unique name, but you can still use your email address.
IMAP (Incoming Mail Server) information:
• Server name: imap.mail.me.com
• SSL Required: Yes
• Port: 993
• Username: [email protected] (use your @me.com address from your iCloud account)
• Password: Your iCloud password
SMTP (outgoing mail server) information:
• Server name: smtp.mail.me.com
• SSL Required: Yes
• Port: 587
• SMTP Authentication Required: Yes
• Username: [email protected] (use your @me.com address from your iCloud account)
• Password: Your iCloud password
Also, you must upgrade your password to meet the new criteria:  8 characters, including upper and lower case and numbers.  If you have an older password that does not meet these criteria, when you try to setup mail on your mac, using all of the IMAP criteria listed above, it will still give a server error message.  Go to   http://appleid.apple.com         then follow directions to change your password, then go back to setting up your mail using the IMAP instructions above.
Thanks to dpepper...
https://discussions.apple.com/thread/3867171?tstart=0