Error validating a inputbox with regular expressions

Dear experts:

Hope you are having a great week!

I'm having a hard time validating the information provided on an inputbox, it must be an email from the outlook domain. This is the code I'm using to evaluate the email provided (ROemail)

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The Function ValidateEmailAddress() that validates the String goes like this:

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But for some reason it's not working and it's sending me this errors related to the objRegExp, It's the first time using a function and a Regular Expression so I'm not sure if I'm doing something wrong or something is missing.

Could you please advice me?

Thank you so much in advance!

It may be easier to use the Like operator to validate...

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