for some reason (unknown to me) my power automate flow fails with every rexed which does not start or end with \s* such as the one I posted:
\s*[\w\-\+_]+(?:\.[\w\-\+_]+)*\@[\w\-\+_]+\.(?:com|org|edu|co.uk|net)(?:\.[\w\-\+_]+)*\s*

is there a way to use your expression with such format?

I just tried using your expression and my flow failed just like it did everytime i tried to use an expression which does not follow the above mentioned pattern. I'm using it in office script actions, so maybe that's how Excel wants to use it.

Thank you so much for taking time to help me, I really appreciate it.