Apple Mail error for signed messages

[deesto]

Apple Mail wouldn't display encryption options using my certificate, which was valid and not expired, in my Keychain. I realized that it had to do with my email address: my actual address is much longer than my mail alias, which I like to use as my outgoing address since it's easier to remember. I used my real address, and not the alias, when requesting the certificate, and I assume this is why Mail wouldn't accept the certificate. But I didn't see any errors when starting Mail, nor anything Mail-related in the console.

I re-applied for my certificate, so that now the email addresses match and Keychain calls the cert "valid", and Mail recognizes the cert and attempts to sign messages with it. But now, when I try to send a message with a signature, I get "Operation could not be completed (MFMessageErrorDomain error 1035.)". I've read that deleting your existing mail password from your Keychain and then re-adding it should solve this problem, but it doesn't work. I've tried deleting the password, the cert and key, re-importing the cert, and letting Mail add the password back to the Keychain, but the error remains. Nothing Mail related appears in the console.

Is there anything else I can try, aside from deleting the entire Keychain and starting from scratch (which would be quite painful)?