When I upgraded to Thunderbird version 91, I can no longer receive encrypted e-mails. The error message says that the e-mail does not contain a digital signature. However, when I view the e-mail using Outlook it clearly does have a valid digital signature. I tried sending a signed and encrypted e-mail to myself and others, and everyone else received it but I cannot read it because it says it does not have a digital signature. It worked fine before this recent upgrade.