Outgoing email hangs Mail permanently -- too many photos.
I put 20 or so photos copied from Messages in an email to myself as a way to move them into Photos. The size was too big to go through my server. Mail froze and I was not able to click on anything in Mail. I forced quit it but as soon as it re-opened, the problem was still there -- the email I tried to send with the warning about size. I forced quit again and waited a half-hour and tried again -- same problem.
Mac OS Sierra. 10.12.6.
iMac 21.5″, macOS 10.12