I got a problem with some smtp settings in my craft 3.5.14. The domain of my client uses special characters like (ö, ä, ü) and therefore for their email addresses. In this case my client only use the character "ö". When using those email addresses for authentication I always get an error when testing it in craft (settings/email). I can't find anything in the logs. Is it generally possible to send emails with special characters in their domain? Something to watch out for? I also tried to convert the email address into ace through an idn converter. No success. When using another provider on another domain without special characters the sending of emails works. Thx for you help!