Re: [Django] #35378: Incorrect folding of long address headers with special characters when using 7bit Content-Transfer-Encoding in EmailMessage (was: Bad UTF-8 "To" header encoding in EmailMessage)

[Django]

#35378: Incorrect folding of long address headers with special characters when
using 7bit Content-Transfer-Encoding in EmailMessage
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Reporter: andres | Owner: nobody
Type: Bug | Status: new
Component: Core (Mail) | Version: dev
Severity: Normal | Resolution:
Keywords: | Triage Stage: Accepted
Has patch: 0 | Needs documentation: 0
Needs tests: 0 | Patch needs improvement: 0
Easy pickings: 0 | UI/UX: 0
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Changes (by Sarah Boyce):

* cc: Florian Apolloner, Joachim Jablon (added)
* stage: Unreviewed => Accepted
* summary: Bad UTF-8 "To" header encoding in EmailMessage =>
Incorrect folding of long address headers with special characters when
using 7bit Content-Transfer-Encoding in EmailMessage
* version: 5.0 => dev

Comment:

Thank you for the report!
I can replicate and the discussion in https://github.com/anymail/django-
anymail/issues/369 is also very useful, thank you.

> I'm pretty sure the problem only occurs with Python email's legacy
`email.message.Message`, which uses a
[https://docs.python.org/3/library/email.policy.html#email.policy.Compat32.fold
different folding algorithm] (via `email.policy.compat32`) than modern
`email.message.EmailMessage` (`email.policy.default`) uses.
> My understanding is the Compat32 legacy layer is there specifically to
replicate Python 2's email behavior (including any bugs), so there's not
much point in reporting bugs against it.

Agree that #31784 is also somewhat related.
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Ticket URL: <https://code.djangoproject.com/ticket/35378#comment:1>
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