Adobe Acrobat - text box - e-mail validation

Hello,

I want to create a textbox where the user can only type in a e-mail adress.
First I tested it with the format. But the user-specified formats "O@O.A" or "X@X.A" are not a solution.

I'm not the specialist for JavaScript for Acrobat API but I hope, someone can help me to find a solution.

My idea is probably understandable.

$local_part$ + "@" + $domain_part$

and $domain_part$ contains a dot (".") and the part after the dot must have two and can have maximum three letters.

I hope someone can help me.

Thanks in advance,
ben justus bremer