Validation Regex For Re-Entry Of Email Address Field?

I am wondering if there is any code I can enter into the Validation Regex box of a field so that it will look to see that the text/data being entered into the field is the same as the text that was entered into the previous field?

I have set up a field for people to enter their email address a second time to avoid errors, but the problem is the field does not check to see if the email address entered in the second field matches the first field.

I have had people enter two different email addresses and, since the second field does not compare the data against the first field, you end up with people making errors which aren’t prevented by the form and could in fact result in a user even entering an incorrect email address twice.

Any solutions offered would be much appreciated.

Thank you.