Ok, I wasn't clear enough as to what to do. Try it this way.
Check If Your Account is Using the Email Servers
To check if all servers are in use by your accounts, open Mail preferences, click Accounts, then click Account Information. From the Outgoing Mail Server (SMTP) pop-up menu, choose Edit Server List to display a list of servers. If you see an entry in the “In Use By Account” column for a server, that server is in use. If you have any servers listed that don't have an entry in this column, select the server, click Remove Server, and then click Done. If you see that your affected account isn't “In Use,” go back to step 5 to reset your server settings.
Reset Your Email Account
Try deleting your email account from Mail and then setting the account back up again. Before you do this, save all messages that you want to keep in a different mailbox on your Mac (to create a new Mailbox, choose New Mailbox from the Mailbox menu, choose On My Mac from the Location pop-up menu, type a name for your mailbox, click OK, and then drag the messages that you want to keep to this new mailbox). To delete the account, choose Preferences from the Mail menu, then click Accounts. Make note of the information for the account you want to reset, then select the account in the Accounts list and click the remove (-) button. To recreate your account, click the add (+) button and reenter the information for your account. You can then drag all of your messages from the alternate mailbox back into your newly recreated account.
I had that same problem and it was an easy fix once I figured it out but like an idiot I didn't write it down so had to go through the same steps we are now.
The upside to this is we are very close to the fix. I hate admitting I don't know everything.