Non-stop popups in Mail for 'The IMAP command "APPEND" (to INBOX) failed with Server Error: Server Busy

I keep getting these error messages and they seem to be repeatedly for a few different emails that I deleted previously. If I leave Mail open for long, the popups stack up and I have to spend time playing whack-a-mole to get rid of them. https://preview.redd.it/v6rpm5keya9e1.png?width=520&format=png&auto=webp&s=3dd6b7ab0f815cfda9cf437c4b61dbe9e87a1eb3 And then, any emails that I have moved or deleted since the last time I closed the popups are all magically back in my inbox, so I've deleted the same emails 10x. I've searched for a solution, but haven't found anything. It looks like someone had a similar issue with sent messages a few years ago, but that suggested fix didn't work. I've also tried removing iCloud mail, restarting and turning iCloud mail back on. At this point, Mail on my Mac is useless, so I would really appreciate any suggestions. Thanks MacOS 15.2 Sequoia on M2 MBP. Mail Version 16.0 (3826.300.87.4.3)