This is how you build an incorrect password notification.

No, I’m not trying to turn this into a design blog. I just want to give Meetup total kudos for having one of the few good “incorrect password” messages ever:

warning box saying this email address has a meetup account, but that was the wrong password

Meetup knows that I’m busy (going to meetups!) and understands that I probably have a lot of accounts online and can’t remember A) if I actually do have an account with Meetup, B) what email I used for it, and C) what password I used for it. They clarify that I do have an account attached to that email but that my password is incorrect. They even kindly remind me that passwords are case-sensitive.

Most password forms give you an unfriendly error message, giving you no clarity on whether A, B, or C is the issue. It infuriates me every time I see it:

login error saying incorrect email, username, or password, please try again

Nice work, Meetup. The fact that you apply your understanding of and care for your customers to such a minor part of your experience is awesome.