List of steps to reproduce (step by step, including full links if applicable):
What happens?:
Lots of characters are the replacement character �
What should have happened instead?:
Characters are correctly encoded
Software version (if not a Wikimedia wiki), browser information, screenshots, other information, etc:
Seems that all list threads sent after the potd tool was restarted on 2021-07-04 are affected, see related task T265568.
Seems to be an issue specifically with hyperkitty (the archives), the actual email looks fine.
It's not that related but the footer in Persian in wikifa-admin-l is all ???? instead (both email and hyperkitty) while the footer file is correct. I think that's a db encoding/decoding issue.
T282621 doesn't seem to have fixed this, it is still happening: https://lists.wikimedia.org/hyperkitty/list/daily-image-l@lists.wikimedia.org/thread/UQBNUCZZ6ECZMMWM2GK23TEEDL2GMAXT/