asp yada php ile regular expression kullanarak yapabilisin
ayrıca bunun için programlarda var

<%
Response.write isValidEmail("david@codetoad.com") & "<BR>"
Response.write isValidEmail("davidcodetoadcom")

Function isValidEmail(myEmail)
dim isValidE
dim regEx

isValidE = True
set regEx = New RegExp

regEx.IgnoreCase = False

regEx.Pattern = "^[a-zA-Z][\w\.-]*[a-zA-Z0-9]@[a-zA-Z0-9][\w\.-]*[a-zA-Z0-9]\.[a-zA-Z][a-zA-Z\.]*[a-zA-Z]$"
isValidE = regEx.Test(myEmail)

isValidEmail = isValidE
End Function%>

Burdan örnek alabilirsin