How to encode international characters in recipient names (NOT addresses) with smtplib.sendmail() in Python 3?

Question

I\'m using a standard smtplib.sendmail() call in my Python 3 program to send emails, as follows:

smtp_session.sendmail(\'The Sender \',          


        

Answer 1

The argument to smtplib.sendmail() should not have human-readable labels, just the address terminus.

smtp_session.sendmail('sender@domain.com', ['recipient@domain.com'],
    'Simple test body here')

The email.headerregistry module in Python 3.6+ has a facility for extracting just the email terminus, by way of parsing structured headers into objects with attributes.

from email.headerregistry import AddressHeader

hdr = dict()
AddressHeader.parse('To: The ÅÄÖ Recipient ', hdr)
for grp in hdr['groups']:
    for addr in grp.addresses:
        print('{0}@{1}'.format(addr.username, addr.domain))

(I really hope there is a less convoluted way to access this functionality but at the very least this produces the expected result.)

In the actual message, Python takes care of properly RFC2047-encoding any headers with Unicode content (if you use the correct methods from the email library to construct a prop0er MIME message); but this is pure presentation (RFC5322) not transport (RFC5321). So in the message itself you might see

From: The Sender 
To: The =?utf-8?Q?=C3=85=C3=84=C3=96_Recipient?= 

though keep in mind that there is no requirement for the message content to actually reveal the transport sender or recipient headers. (Maybe tangentially see Header "To:" for a Bulk Email Sender)