Regular Expression

[a-zA-Z0-9!#$%&'*+\-/=?^_`{|}~]+(?:\.[a-zA-Z0-9!#$%&'*+\-/=?^_`{|}~]+)*@(?!-)[a-zA-Z0-9-]+(?:\.[a-zA-Z0-9-]+)*[a-zA-Z]\.[a-zA-Z]{2,}