We now have support for EAI (RFC 5336 SMTP Email Address Internationalization), as I accomodated the patch of Arnt Gulbrandsen into my qmail distribution (Nov 03, 2024 and later versions). This means that from now on addresses containing UTF8 characters like mimΓ¬@domain.tld or even ΰ€ΰ€°ΰ₯ΰ€¨ΰ₯ΰ€@ΰ€―ΰ₯ΰ€¨ΰ€Ώΰ€΅ΰ€°ΰ₯ΰ€Έΰ€².ΰ€ΰ€Ύΰ€°ΰ€€ will be accepted provided that the remote server advertises the SMTPUTF8 verb after the MAIL FROM. If the remote server doesn't advertise SMTPUTF8 capabilities, then the conversation goes as in the past with no allowed UTF8 characters in the email addresses, with a few exceptions for special chars likeΒ $%?*^~&/\Β£#+_-.=
I also had to modify the Mail Address Verification program shipped by chkuser because, if activated by defining the CHKUSER_SENDER_FORMAT and/or CHKUSER_RCPT_FORMAT variables, it accepted only ASCII characters plus a small set of additional UTF8 in user and domain names. And since I was there I simplyfied the code dropping a couple of functions and variables.