If I create a message this way (using real addresses, of course):
msg = email.message.EmailMessage()
msg['From'] = "sender@example.com"
msg['To'] = "recipient@example.com"
msg['Subject'] = "Ayons asperges pour le déjeuner"
msg.set_content("Cela ressemble à un excellent recipie déjeuner.")
I can successfully send it using smtplib. No problem with the Unicode characters in the body. The received message has these headers:
Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable
If I try to create the same message in this alternative way:
msgsource = """ From: sender@example.com To: recipient@example.com Subject: Ayons asperges pour le déjeuner Cela ressemble à un excellent recipie déjeuner. """ msg = email.parser.Parser(policy=email.policy.default).parsestr(msgsource)
I can’t send it. send_message() from smtplib fails with
UnicodeEncodeError: 'ascii' codec can't encode character 'xe0' in position 15: ordinal not in range(128)
and obviously expects ascii, not Unicode. What causes the difference and how to fix it properly?
(code is based on these examples)
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Answer
The error can be avoided by encoding msgsource and then parsing the resulting bytes:
msgsource = msgsource.encode('utf-8')
msg = email.message_from_bytes(msgsource, policy=policy.default)
print(msg)
outputs
From: sender@example.com To: recipient@example.com Subject: Ayons asperges pour le =?unknown-8bit?q?d=C3=A9jeuner?= Cela ressemble �� un excellent recipie d��jeuner.
sending it to Python’s SMTP DebuggingServer produces
b'From: sender@example.com' b'To: recipient@example.com' b'Subject: Ayons asperges pour le dxc3xa9jeuner' b'X-Peer: ::1' b'' b'Cela ressemble xc3xa0 un excellent recipie dxc3xa9jeuner.'
Note that no encoding headers are written: I’m guessing that the parsers attempt to reproduce the message from the source string or bytes as faithfully as possible, making as few additional assumptions as possible. The Parser docs
[Parser is] an API that can be used to parse a message when the complete contents of the message are available in a [string/bytes/file]
seem to me to support this interpretation.