Mail not working right

I have been having two issues with the Mail app.

One thing that happens often is that will not send mail right away but park it in an "outbox". Eventually it goes, sometimes after I quit and restart Mail and others when the computer wakes from sleep.

The other issue is that a small minority of mail items will not let me move them to the trash file so I can dump them. I have attached the error message I get.

Also, this is with only on my IMac, but I can't figure out how to move this to that thread.

Thanks for all the help.