I'm trying to send mails using smtplib in a way that displays to the user real name (like the Gecos field in /etc/passwd). To accomplish that, I use Something <user@example.com> as value of From: header.

I'm trying to do this:

to = 'test@wikimedia.cz'
from_mail = 'info@wikimedia.cz'
from_name = 'Sender Name'
mailtext = 'Příliš žluťoučký kůň úpěl ďábelské ódy'

s = smtplib.SMTP('smtp-relay.gmail.com')
s.ehlo()
s.starttls()
msg = MIMEText(mailtext, _charset="utf-8")
msg['Subject'] = '(bez předmětu)'
msg['From'] = '%s <%s>' % (from_name, from_mail)
msg['To'] = to
s.sendmail(from_mail, to, msg.as_string())
s.quit()

This works correctly, as you can see on a screenshot of my Gmail. However, if from_mail is "Jméno Odesílatele" (which includes non-ASCII characters), the mail a) gets redirected to Spam folder b) doesn't display "Jméno Odesílatele" as sender's name, see screenshot.

As you can see, mail text can contain non-ASCII characters with no problem. Also, Subject containing non-ASCII characters with no problem. But From containing non-ASCII doesn't work.

• Headers of wrongly displayed mail


• Headers of correctly displayed mail

Update 2018-11-10

Updated the code snippet to include real data, like the mailserver I use.

I tried to use msg['From'] = Header('%s <%s>' % (from_name, from_mail), 'utf-8'), msg['From'] = Header('%s <%s>' % (from_name, from_mail), 'utf-8').encode() and a instead of msg['From'] = '%s <%s>' % (from_name, from_mail), the result is the same.

If anybody's interested, my real code is on GitHub.