This pattern can be repeated one or more times, and must be followed by the top-level domain name. To include them in a regular expression library, either copy and paste the code into a Visual Studio Class Library project, or copy and paste it into a text file and compile it from the command line with a command like the following (assuming that the name of the source code file is Regex or Regex Utilities.vb: You can also use the Regex.
If the character that follows @ is not an opening bracket, match one alphanumeric character with a value of A-Z, a-z, or 0-9, followed by zero or more occurrences of a hyphen, followed by zero or one alphanumeric character with a value of A-Z, a-z, or 0-9, followed by a period. To determine whether an email address is valid, pass the email address to the Mail Address. methods can be included in a library of regular expression utility methods, or they can be included as private static or instance methods in the application class.
If it all works, you can continously monitor your address list to ensure email addresses continue to be valid - Some mail servers may return a positive response even if the mailbox doesn’t exist.
Just an FYI: I'm the author of Mime Kit which has already been mentioned on this thread.
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).
But what if I told you there were a way to determine whether or not an email is valid without resorting to regular expressions at all? The activation email is a practice that’s been in use for years, but it’s often paired with complex validations that the email is formatted correctly.
It’s surprisingly easy, and you’re probably already doing it anyway. If you’re going to send an activation email to users, why bother using a gigantic regular expression?
If the first character is a quotation mark, match a beginning quotation mark followed by at least one occurrence of any character, followed by an ending quotation mark.
Think about it this way: I register for your website under the email address . That’s probably going to bounce off of the illustrious mail daemon, but the formatting is fine; it’s a valid email address.
To fix this problem, you implement an activation system where, after registering, I am sent an email with a link I must click.
The result of sending an email to a badly formatted email address would be the same: it’ll get bounced. If you really want to do checking of email addresses right on the signup page, include a confirmation field so they have to type it twice.
If your user enters a bad email address, they won’t get the activation email and they’ll try to register again if they really care about using your site. Enterprising individuals will just copy and paste, but what it comes down to is this: if your user enters a bad email address, you shouldn’t make it more of a problem for yourself than you have to.