I have a question about sending emails in a FastAPI application. We integrated Yandex360 to have the mail on the domain name of our website. The problem is that the website address is Cyrillic. Of course, you can access it through Punycode.

I tried the fastapi-mail library. Here’s the link to it.

I created an application password, set up the client itself. But when I try to send a message, I get the following error: “Address containing non-ASCII characters was provided, but SMTPUTF8 is not supported by this server.”

I thought it might be a problem with Yandex’s SMTP server. I wrote to support, but they gave me this answer:

“We apologize for the delay in responding. We do not see any restrictions on sending emails from admin@шахматыекб.рф on our end. You can check if it works in the latest version of the same Outlook, it should work.
It is possible that the problem is in the library you are using. Judging by the error, the program is passing the address not as ASCII characters, despite the fact that the address is specified using Punycode. Unfortunately, in this case, we can only recommend referring to the documentation of the library and cannot help with setting up third-party programs.”

Perhaps someone can suggest a library for a FastAPI application that can integrate with Yandex mail and works with Cyrillic addresses?