Action Mailbox mistakes attachment as body if no body exists

[HashNotAdam]

I created issue 50755 on the Rails project, which relates to an issue whereby Action Mailbox does not parse an attachment if the email has no body.

There has been a suggestion on the issue that this relates to an incompatibility with emails from SES. If this is true, I would be happy to work on the problem, but I'd like to verify that it is an SES-specific issue, and not an issue that could occur with other providers (and therefore should be fixded in Rails)

[HashNotAdam]

It appears this is a problem in the Mail gem. Unfortunately, someone found a solution in 2017, but the PR has never been completed