It seems that after T66795: Email server's DMARC config prevents users from sending emails via Special:EmailUser the From: is (wikiname) <wiki@wm.o>. However, setting sender name as (wikiname) is not useful as I can't know who sent it until I see the footer of the whole email. So, I'd like to see the sender's name instead of the wikiname, or something like (sender) from (wikiname), which will be lot better.