How to match a comma separated list of emails with regex?

Question

Trying to validate a comma-separated email list in the textbox with asp:RegularExpressionValidator, see below:

Answer 1

^([\w+-.%]+@[\w-.]+\.[A-Za-z]+)(, ?[\w+-.%]+@[\w-.]+\.[A-Za-z]+)*$

Works correctly with 0 or 1 spaces after each comma and also for long domain extensions