Signing in with Google now confirms your email address. If the account's email was not yet confirmed and it has a password, that password is removed, every session on the account is signed out, and any pending email change is cancelled, because nobody proved who chose the password. Google sign-in is refused when Google has not confirmed the address itself. Using a sign-in link on an unconfirmed account works the same way. Accounts already linked to Google whose address was never confirmed are corrected once when this release deploys, and the follow-up and notification emails held back for them are dropped instead of all arriving at once.
Confirmation and password emails now go through the scheduled email queue and are retried when sending fails. Their links are stored only as secure hashes, and asking for a new link makes the older one stop working. The email confirmation page confirms your address only when you press Confirm. "Forgot password" can set a first password for an account that signs in with Google, choosing a new password through its link signs out every session on the account, and account settings links to "Forgot password" whenever you want to set or change one.
Every email now includes a plain-text version, and text you typed can never become a link or formatting in an email. Unsubscribe links show a confirmation page before anything changes, and mail apps can unsubscribe you in one click. The unsubscribe links in weekly check-ins and outcome follow-ups, which led to a "not found" page, now work.