email.utils.make_msgid return ids that break email messages with related content

Bug report

I have been trying to replicate the examples listed here: https://docs.python.org/3/library/email.examples.html

For some reason the one about "creating an HTML message with an alternative plain text version" is assembling an email message that Thunderbird (and other email readers) does not display correctly, as images are not displayed and marked as broken.

The example uses make_msgid() to generate content ids.

Python 3.10.9 (main, Dec  7 2022, 03:14:04) [Clang 13.0.0 (clang-1300.0.29.30)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> from email import utils
>>> utils.make_msgid()
'<167119948916.50921.14529814791249370642@1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa>'
>>>

Turns out that for some reason the string is too long, because if I either remove the domain part or purportedly shorten it, e.g., make_msgid(domain="0.0.0.ip6.arpa"), then everything works again and the resulting email can be correctly displayed in Thunderbird/Outlook.

Your environment

• CPython versions tested on: 3.10.9
• Operating system and architecture: OSX/M1

Linked PRs

• gh-100856

まず email.examples.html の例から Thunderbird/Outlook の失敗を再現し、特にデフォルトドメインを使用した場合の email.utils.make_msgid() を調べます。生成された Content ID を短縮ドメインの場合と比較します。完了の条件は、例が関連コンテンツのメッセージを生成し、メールリーダーで正しく表示されることです。