When there are non-ASCII characters in an email subject line, the entire subject should be encoded as UTF-8 so that it will display properly for the recipient. I received email from InternetArchiveBot about a submission for the Turkish Wikipedia with "Subject: Bot iÅŸiniz 18485 tamamlandı!" and about one for the Italian Wikipedia with "Subject: La tua attività di bot 16464 è stata completata!" The corresponding text in the body of the message displayed properly, with all the diacritical messages where they should be: La tua attività di bot 16464 è stata completata! I use gmail, so it's possible that gmail is doing something wrong.

This page explains what to do: https://www.telemessage.com/developer/faq/how-do-i-encode-non-ascii-characters-in-an-email-subject-line/ and the service at https://www.sendblaster.com/utf8-email-subject-encoder/ will encode a subject line, one line at a time, so that "Subject: La tua attività di bot 16464 è stata completata!" would become Subject: =?UTF-8?B?TGEgdHVhIGF0dGl2aXTDoCBkaSBib3QgMTY0NjQgw6ggc3RhdGEgY29tcGxldGF0YSEg?= Eastmain (talk) 20:56, 30 March 2024 (UTC)

And sure enough, we checked the logs and they are not being sent out in UTF-8.