I noticed my AT&T ISP email account settings changed after enabling SpamSieve. Specifically, Accounts->Advanced->Authentication changed from Password to “external (tis client certificate)”. (I noticed this while chasing down a failure on one of the accounts, which fixed itself; Yahoo isn’t too reliable).
I found no mention of this in the manual or forum. Can you explain what’s going on? (SpamSieve works fine; just trying to understand.)