On submission, if the two email fields do not match the registration will not process and the form will reappear with a message indicating those two email addresses did not match.
The remaining fields and choices will still retain previously filled in information. The user will just need to correct the email addresses and re-submit.
This DOES work with the register after posting feature. When the user enters their email address and post content and then hits save, they are taken to the usual user registration form with the email address field pre-filled with their entry. The confirm email field is beneath, and works, as expected.
This validation occurs AFTER a user submits the registration form, not via jQuery live on the form after they enter both email addresses.
Also important: Users of IPS Commerce can require purchases of items on registration, the user registration form created by Commerce for checkout purposes does NOT get this email validation form field, and likely never will (reasons...). Feel free to lobby IPS for a built-in email validation field!
Version 2 is for Invision Community 4.4 and above exclusively. Confirmed working with 4.5
For 4.3.6 and lower please use version 1.
This is a free resource, written a long while back, with the expectation that IPS would build in this feature themselves eventually.