Problem with sending mail after downloading El Capitan on MacBook Pro. How can I fix it?

[iMore Question]

Problem with sending mail after downloading El Capitan on MacBook Pro.

Can receive mail but when I go to send, I get a prompt requiring my password; after putting it in, it comes back saying pw is incorrect. I just changed it so it's definitely correct. Help!

 

[Just_Me_D]

Re: Problem with sending mail after downloading El Capitan on MacBook Pro.

Reboot your MacBook Pro and then try again.

 

[snfaircloth]

Thank you, I already tried it and it didn't work but tried again and still get same message