So I open Apple Mail after awhile of not using it and I am overwhelmed with multiple windows and errors and I am not sure how to get rid of them without clicking on them one by one. See attached screenshot.
MacBook Pro with Retina display, OS X El Capitan (10.11.5)
How was this issue resolved?
Try Mail/Preferences/Accounts /Account Information. Select an account, then go to Outgoing Mail Server (SMTP). From the drop down menu select Edit SMPT server list. Then set up a server for each mail account so that is associated with the e-mail address. Then go to each account and set that server as the Outgoing Mail Server (SMPT). You can click Use only this server if desired.
Mac Apple Mail cannot send message preferred outgoing server
