Please review this PR when you have time @taleinat :D

You don't need to create a new PR in order to address review comments. Just update the original PR.

Hello, @ZackerySpytz , I use a wrong branch name at the very beginning then deleted it locally by mistake. That is why I use a new PR here.

Python 3.8.0 is still impacted by this.

Patched version 3.8.0 accept passwords with utf8 chars.

Hi,
I just wanted to give some motivation: I had a special character in my password and it took some time until I have figured out, what was going on. It would be great, if this patch could be reviewed!
Thank you all!

Hello, lovely Python dev folks,
as another affected individual I wanted to ask, if this topic is still alive?
Thank you so much for the contributions!

Let smtplib support non-ASCII passwords, better
smtplib support for UTF-8 passwords

Closing in favor of SASLprep-based gh-103611.