Sending signed emails are silently ignored

[WilfSilver]

Prerequisites

• I have searched open and closed issues to make sure that the bug has not yet been reported.

Bug report

Describe the bug

When sending a signed email via SimpleLogin (e.g. replying to a forwarded email after telling Proton Mail to sign all outgoing emails), the email is silently ignored and not delivered.

Expected behavior

Either to send an email to report the error to the sender (similar to the one sent when you send an email via SimpleLogin with an email address which is not on your account) or unsign the email and deliver it as usual?

Environment (If applicable):

• OS: Linux
• Browser: Firefox
• Version 121.0

Additional context

I have reproduce this lack of communication with:

• Replying to a forwarded email
• Sending a new email via the contacts feature

Proton Mail also has the feature of including a public key by default in the attachments, if there is a way to continue forwarding the email, it may be worth taking into account these attachments and automatically removing them (however at that rate you may as well just return an error)