Trying to match these restrictions is a complex task, often resulting in long regular expressions. NET Framework regular expression classes are part of the base class library and can be used with any language or tool that targets the common language runtime, including ASP. The following C# source code shows how to validate an email address with the help of regular expressions.
This method validates that e-mail addresses have the form "[email protected]".
If you want to validate email addresses entered into your form but avoid complicated tinkering and scripts, HTML5 lets you rely on the browser — without effort, and without turning to Java Script.
Browsers that do not recognize type="email" should (and, as far as one can tell, all will) treat the input field like an ordinary type="text" field.
To get a valid email id we use a regular expression /^\w ([\.-]? Please try again in a few minutes: if the problem persists, then the domain for the email address can't accept email messages.A socket connection error occured while connecting to the mail exchanger which serves the email address domain.Please try again in a few minutes: if the problem persists, then the domain for the email address can't accept email messages. This is not an indicator that the mailbox actually exists (or does not) but, often, a message sent by external mail exchangers with greylisting enabled.To complete the validation of the address you should re-process the verification within a small delay of time (usually 5-10 minutes), until the server answers with a different message.