Mail keeps bringing up new mail window that can't be closed

RobertBocce wrote:

As I'm in any part of mail, new windows keep piling up and they can't be quit until I quit Mail.

Mail

drafts / blank windows /untitled

I would look for an unsent email stuck in the Outbox of one of your email accounts. Remove the unsent email typically fixes the issue.

Delete the mail from the Outbox. If you do not see it, quit the Mail.app and relaunch it holding down the Shift key . The Outbox should appear.

RobertBocce wrote:

LeroyDouglas... thanks for the solution... it was aggravating!!! Bob

Good computing RobertBocce— thanks for corroborating the correct solution above