This is what I'm currently working with:
((?i)(\w|^){0,25}[0-9]{3})[^\.]*@(gmail)\.com
What I'm attempting to do is block any email that is any amount of characters but with 3 numbers trailing the characters.
This works. HOWEVER, when Google creates a username for people, it usually chooses firstname.lastname###@gmail.com. I don't want an email with a period before the @gmail.com to be included.
I have played and played with this expression, and I can't get it. So for example [email protected], the expression is tagging everything after the period. I need for the regex to check the ENTIRE email and check to see if it follows the expression. I know there is this tidbit ^[^\.]*$ but I have no idea where to put it.
You could match 0-25 word characters followed by 3 digits \w{0,25}[0-9]{3} and use anchors to assert the start ^ and the end $ of the string.
^\w{0,25}[0-9]{3}@gmail\.com$
If you want to make use of the negated character class [^ you could match 0-25 times matching any char except a whitespace char, @ or a dot followed by 3 digits using [^\s@.]{0,25}[0-9]{3}
^[^\s@.]{0,25}[0-9]{3}@gmail\.com$