I have to write a program to verify email address availability. i have to
verify thousand of email address. is there any way to verify the email in
.net instead. the requirement is to verify which email valid or invalid
Depends exactly what you mean...
Validating whether a piece of text "looks like" an email address is a fairly
trivial exercise - do a Google for email validate RegEx
If, however, you mean that in addition to the above you need to validate
whether an email address has already been used or not, then that will be
next to impossible depending on the host of the domain and the software
installed on the mail server...
Also, don't forget that most mail servers have a 'catch-all' facility which
makes <anythingyoulike>@domain.com a perfectly viable email address... In
this instance, individual mailboxes are not required, so there would be
nothing for you to check...