ASM Parameter Value not matching regex

I'm trying to validate a username parameter. Goal is to make sure the username is in email format. I mentioned in Block Settings to alarm for parameter not matching regex and under parameter I'm using userinput for following regex

"[‎9/‎27/‎2017 4:46 PM] Prabhakaran, Sridhar: ^[a-zA-Z0-9.!$%&'+/=?^_`{|}~-]+@?(?:.?)$ "

I still dont see the violation in logs. Any thoughts what I missed?