Try the below code for email is format of
[email protected]
1st part -jsmith
2nd part [email protected]
1. In the 1 part it will allow 0-9,A-Z,dot sign(.),underscore sign(_)
2. In the 2 part it will allow A-Z, must be @ and .
^[a-zA-Z0-9_.]+@[a-zA-Z.]+?\.[a-zA-Z]{2,3}$