There's another catch, many services use the email address as an immutable identifier that cannot be changed. For some that doesn't matter, but at the very least it is a lot of time/effort.

When I switched away from Gmail, I used my password manager to track the logins I needed to change. Then, just monitored the Gmail inbox for anything I missed.

Unlike sibling commenters, I used to not use a password manager. (But do now!)

I just keep the old GMail for now, and whenever I receive a valid email there, I visit the sender website to update it.

This depends on you remembering your "low-volume important accounts" like government websites you visit once a year, but otherwise, I would not cry if my imgur account got lost or something eventually.

Would be nice for companies to maintain a standard account management API which password managers could call. Imagine buttons on your password manager: "Set All Emails..." and "Randomize All Passwords..." I didn't find any such standard after a quick search.

Edit: Looks like LastPass does it with a screen scraper https://support.logmeininc.com/lastpass/help/how-do-i-update...

First, I saved every login on Bitwarden and then used that to visit every website and changed login email info there and re-saved on Bitwarden.

The effort is only one time or one day at max. And the rewards are worth the time.

Yes, my password manager