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

首先从 email.examples.html 示例中重现 Thunderbird/Outlook 的失败，并检查 email.utils.make_msgid()，尤其是在使用其默认域名时的情况。将生成的内容 ID 与缩短域名的情况进行比较；当示例生成的相关内容消息能够由邮件阅读器正确显示时，即视为完成。