How-To’s
How-To’s Guides
https://www.movavi.com/support/how-to/how-to-convert-mov-to-mp4.html
https://cloudconvert.com/mov-to-mp4
http://video.online-convert.com/convert-to-mp4
https://www.youtube2mp3.cc/
The solution is to reduce the maximum number of connections in Thunderbird. This can be done from
Edit > Account Settings > Server Settings (for the account) > Advanced > Maximum Number of server connections to cache.