Thank you for your feedback. This is an excellent idea. I'm going to take this back to our design team. I'm also going to open this page for voting so that other customers can voice their feedback too.
Over the last week, I've seen multiple phishing attacks using what appear to be compromised Constant Contact accounts. It's possible accounts have been compromised through password spraying or using credentials that have been obtained from other breaches (password reuse).
Since Constant Contact is considered a trusted platform, phishing emails may bypass some of the usual controls.
While 2FA isn't a panacea, it prevents accounts from being easily compromised using the methods I mentioned above.
I would like to suggest that two-factor authentication support be added to your product. Our account was recently hacked and an embarrassing was sent out.
We need to secure our environment beyond username and password.