DKIM body hash fails for multipart messages without closing boundary

[breedbekkikker]

MimeKit always adds the closing boundary when reserializing a multipart message, even if the original message body does not contain the closing boundary. Some signed email therefore actually fails DKIM body hash validation.

[jstedfast]

Would you be willing to generate a sample message for this issue so that I can add it to my unit tests?

I was actually thinking about this potential issue the other day.

I think what I'll have to do is have the parser set a flag on the Multipart to specify whether an end boundary should be used.

[jstedfast]

FWIW, I think S/MIME and PGP/MIME will also be affected by this.

[breedbekkikker]

Here is a sample message signed by Gmail which you might want to include in your unit tests.
email.txt

[jstedfast]

Awesome, thank you :)

[jstedfast]

This should also be fixed in MimeKit 1.2.20