I've tried this pattern with regex101.com and it seems to be working as described:

 example@___.com - no match 
 [email protected] - no match 
 [email protected] - match 
 [email protected] - match

So the regex itself seems to be "correct" - could it be that the issue is somewhere else in the code?

As a side note - it also matches lines like:

example@./com
example@x com

Dot . outside of character class construct [] means "any character". If you want it to match exactly dot character and nothing else, escape it with slash: \.