id summary reporter owner description type status component version severity resolution keywords cc stage has_patch needs_docs needs_tests needs_better_patch easy ui_ux 35378 Incorrect folding of long address headers with special characters when using 7bit Content-Transfer-Encoding in EmailMessage andres "Hi! I'm getting errors when trying to send email messages when the ""to"" header has non-ASCII chars. The problem seems to happen when all these conditions are true at the same time: - the readable name part of the recipient is big (e.g. ""A very long and big name for this recipient"" ) - there is at least one non-ASCII char - there is at least one ""special char"" (only seems to happen with comma or parenthesis) - the special char isn't close to or between no-ASCII chars Code example: {{{ import email from django.core.mail import EmailMessage recipient = '""A véry long name with non-ASCII char and, comma"" ' msg = EmailMessage(from_email='from@example.com', to=[recipient]).message() msg.policy = email.policy.default.clone(cte_type='7bit') print(msg.as_bytes()) }}} That prints a bytes string with: `\nTo: A =?utf-8?q?v=C3=A9ry?= long name with non-ASCII char and, comma\n \n` It has an unprotected comma, and the message is rejected by ESPs. Using default policy fix this problem, but possibly causes other bad consequences: `\nTo: =?utf-8?q?A_v=C3=A9ry_long_name_with_non-ASCII_char_and=2C_comma?=\n \n` More details here: https://github.com/anymail/django-anymail/issues/369" Bug closed Core (Mail) dev Normal invalid email, compat32 Florian Apolloner Joachim Jablon Mike Edmunds Accepted 0 0 0 1 0 0