Mail: Unable to verify message signature

swyates wrote:

When I send mail to others (and even when I send to myself) an error message says "unable to verify message signature."

Try deleting the signature and compare your results...

then add a signature back in an test. Seems definitive enough, go from there, make changes if necessary

Create and use email signatures in Mail on Mac - Apple Support

swyates wrote:

That didn't work, unfortunately. Seems something to do with a digital security "signature" and not the text type that we can add?

Can you clarify this is the macs Mail.app...?

if this is through a browser—then try a different browser.

swyates wrote:

Correct. Mail App on iMac and MacBook Pro.

If Mail on your Mac can’t verify a signed email

https://support.apple.com/guide/mail/if-mail-cant-verify-a-signed-email-mlhlp1199/mac