Thunderbird doesn't trust a valid CA Certificate
So basically I sent a digitally signed email using a certificate issued by Sectigo RSA Client Authentication and Secure Email CA.
Now the recipient of the email replied to me with a certificate issued by COMODO RSA Client Authentication and Secure Email CA, but it says the Digital Signature is invalid? Why is it invalid?
I got an error when I try to reply back with a digitally signed and encrypted email:
Sending of the message failed. You specified encryption for this message, but the application failed to find an encryption certificate for johndoe@gmail.com
What I have tried so far:
Exported the .crt then import it on "Manage Certificates" People's Tab
But still got an error when trying to reply to the email
Wšykne wótegrona (2)
Here's a screenshot, it doesn't trust COMODO CA
Please stick to your original topic at https://support.mozilla.org/en-US/questions/1250241