Validating an email address exists
If the user is going to be entering an e-mail address in, it should be his or her responsibility to ensure that it was entered in correctly ( You can try one of these free email validation techniques - to track bounced emails, you can build a console app using an open source POP3 library like Indy.
Sockets to download messages - You can then parse the messages to look for bounced emails using a free Mime parsing library like C# Mime Parser, Mime Kit or Sharp Mime Tools - Kit - that some of the components mentioned above haven't been updated in a while, so you'll have to try them out to verify if they work well.
But this takes time, so If mail has to be sent to many, then use asynchronous mails.
Instead, I have another (tiny) library that can be used for that which is written in accordance with the specification: Email Validation It's a fairly simple class that implements an actual email address tokenizer instead of using error-prone regexes that no one seems to ever get Well if an email exists and you are sending the synchronous mail, then synchronous mail will respond only when the email will reach the destination.
That said, I would not recommend the use of Mime Kit for simply validating an email address (it's way overkill).
Instead, I have another (tiny) library that can be used for that which is written in accordance with the specification: Email Validation It's a fairly simple class that implements an actual email address tokenizer instead of using error-prone regexes that no one seems to ever get hello deepak, you cant check that ..because many browsers does not support this kind of functionality ..still you can give it try ..check this : I have been doing the same in my projet.
If an email, is not delivered, then exception occurs e.g "Mail address not found etc..."; In order to validate if the format of the email is correct, then we check via using a Regex.
Another important point to consider is that do you need to be performing this?
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I validate the email address at the client side by using the Regular Expression validator.
Then in the code behind I write the code to send the mail and I am sending synchronous mail (which actually responds when mail is received at the receiver end).