My @thunderbird regularly marks some S/MIME-signed mails with:

"Digital Signature is not valid!"

#TIL the reason: these mails are signed with sha1-algorithm which is considered insecure since TB 115.

There is a config to accept such signatures, see blog.thunderbird.net/2023/10/t…

However, I think the error message:

"There are unknown problems with this digital signature." is suboptimal.

Seems like an easy issue to fix, but on the other hand I was not even able to finde the appropriate repo. 😬

Thunderbird 115 and Signatures Using The Obsolete SHA-1 Algorithm

A change was made in Thunderbird 115.0 that rejects the use of the SHA-1 algorithm in digital signatures of S/MIME emails.

^{Kai Engert (The Thunderbird Blog)}