Sending message at bottom of mail tool bar won't send?

Hi, Ed!

We appreciate the information. If you start up in safe mode, does the issue persist? Safe mode can help us determine whether issues you’re experiencing are caused by software that loads as your Mac starts up. Start up your Mac in safe mode

If the issue doesn't persist in safe mode, restart as normal and see if the issue returns.

We hope you have a great day!

Hello Ed! The folder we're looking for is the Outbox folder, which will appear if there are messages waiting to be sent. Is there an Outbox folder? If there isn't an Outbox folder, does restarting your Mac have any effect on this issue? Log out, sleep, wake, restart, or shut down your Mac

If restarting doesn't resolve the issue, are you able to compose and send any new email?

Cheers!

Hello RhinoEd! Thank you for participating in the Apple Support Communities.

We understand that you see a status of "Sending Message", but you aren't sure what's being sent. We'd like to look into this with you to see how we can help.

If you check the Outbox for any unsent email, do you see a message trying to be sent there? The Outbox will only appear if an email is being sent and will disappear when the email has sent.

Make it a great day!