Regex_ Match for an Email Domain

[cbil]

Hi All, 

I am relatively new to Alteryx and this is my first time trying to use regex.

My work flow allows the user to type in who they would like to email the produced tables to. I want to make sure that an error message is sent if they enter in any email address that does not end in "@gmail.com". I figured out how to have this happen when they enter one address (attached); however, if they enter multiple emails separated by a ";" the formula I have used doesn't check each address and wont display the error.

Based on lots of googling, it seems like I should be using a regex_match formula, but I am unsure how to write out what I am looking for in the "pattern" section. Any help is greatly appreciated! 

[cbil]

Hi again - is there any way to edit the reg ex expression: 

!REGEX_Match([#1], '^(?>[\w+\-.%]+@gmail\.com(?:;\s*|$))+$')

so that it doesn't throw the error message if the user does not enter any email at all. 

For example, if the user is using the app just to generate the excels, but doesn't want to email them to anyone, I want them to be able to leave the email box blank and the workflow still run.