mail-parser treats multiparts as attachments

[ItayBenAvi]

Describe the bug
mail-parser fails on mails that have multipart attachments
mail-parsers fails in core.py:473
Traceback:
AttributeError: 'NoneType' object has no attribute 'decode'

This happens because of recent change in line core.py:353:
"or ported_string(p.get_content_disposition()).lower() == "attachment""

To Reproduce
Create a part which is multipart with content-disposition of attachment

Expected behavior
Payload should be treated as multipart and as attachment

It can be resolved by changing core.py:353 from 'or' to 'and' statement

Raw mail
Un-fortunately, I can't add the mail for security reason.
The mail have a part with the following payload:

• content-disposition: attachment
• p.is_multipart == True

Environment:

• OS: Linux
• Docker: yes
• mail-parser version 4.1.2 (doesn't re-produce on 3.5.0)

[Jimmy-Newtron]

I have an email that has multipart attachments (nested eml files)
and they appears as following:

--010_MR1PPF7C418669F0E3B41E7740AE3F008BF81AC2MR1PPF7C418669F
Content-Type: message/rfc822
Content-Disposition: attachment;
creation-date="Tue, 01 Apr 2025 08:24:29 GMT";
modification-date="Tue, 08 Apr 2025 11:27:28 GMT"

So the attachment is not detected by the following code:

                if content_id and content_subtype not in ("html", "plain"):
                    is_attachment = True
                    filename = content_id
                elif content_subtype in ("rtf"):
                    is_attachment = True
                    filename = "{}.rtf".format(random_string())
                elif content_disposition == "attachment":
                    is_attachment = True
                    filename = "{}.txt".format(random_string())

[fedelemantuano]

Thanks for your contribution.