It began not long before this update, and didn't improve after the update and barely improved after I deleted most of my old emails.
At first, I thought it messed up other apps, but after AppleCare help and waiting a day, that all recovered.
I'm not noticing a problem with any other program - only emails on the desktop.
Except this - possibly unrelated - iTunes has had a problem for a long while now that didn't improve - and I know others using it having the same problem - where you shorten the end of a track and it doesn't always work within iTunes - spins or keeps playing the full end. However, playing on zoom it works fine. So I've found a workaround in holding dances.
I'm not very good at the technical lingo and knowledge, but had an external HD in the past that died and was lucky a techie could save my art and music and programs all from within the computer HD. So very anxious about doing some major change I don't really understand fully.