To sign a PDF document in Adobe Acrobat, I created a Digital Signaure and added it to the file and saved it as an attachement. I then went to my email browser to send it as an attachent. When clicking send, I get the following password request:
"Mail wants to sign using key "privateKey" in your keychain"
This never happened before and I suspect something got changed when creating the Adobe Digital Signature in Adobe Acrobat. In my apple KeyChain I do not have such a passord stored. This problem is only occuring on the email account on my laptop. It is not an issue on other device.
When you open a new email, you can simply deactivate this digital encrypted signing by clicking on the little blue encircled checkmark in the new mail editor window. If you do this, it will stay unchecked for all subsequent emails. So no need to manually delete digital certificates from the keychain.