Q: incoming email, capitalization changes on From:??

Wow, a mailbox Rebuild took care of it! What does that mean - what was it that was causing weird capitalization??

I spoke too soon! 5 minutes later, it took the existing messages in my Inbox and changed the capitalization back to the weird form! Perhaps every time it refreshes?

but it's not misspelled, it's weirdly capitailzed. Does capitalization matter in email addresses? I thought case didn't matter, and if it was in the previous recipients list (which it is by now, since I've gotten a bunch of emails with that capitalization), how did it appear the very first time? Anyway, I followed the instructions on that link: autocorrect does indeed have the capitalized address in it, but when I click on the little arrow, the address that I can remove is the correct (lower case one)! There seems to be no way to remove the capitalized one.

Yep, I removed it, and it's not there any more in the Previous Recipients window, but still incoming emails from that address have this weird capitalization!

just did that; no dice - still showing up partially upper case!

I don't think it can be that because my other machines (laptop etc.) are showing it correct - it's only this one that's showing it that way.

> Have you tried deleting the account and adding it back?

  no; it's a big account and I don't know if it's worth it to go through all that just for the capitalization.

> What shows at System Preferences/Mail, Contacts and Calendars (or Internet Accounts)?

   the correct (no capitalization) email address. Interestingly, I just noticed that in Mail, when I scroll back through the last year of emails, it's showing the From: on those emails weirdly capitalized, even though the problem only started happening in the last week or two. It's like it's back-labeling old emails with this new capitalization.