Raises the SendMailError event when an e-mail message cannot be sent to the user.
Assembly: System.Web (in System.Web.dll)
The method is called when the SMTP Mail service throws an exception. The default implementation raises the SendMailError error and, if the exception is not handled, rethrows the exception while maintaining the call stack.
Examine the Exception property of the SendMailErrorEventArgs object passed as the e parameter to determine the actual cause of the exception. During development, the most common reason that the SendMailError event is raised is that the <smtpMail> section of the Web.config file is incorrect. After deployment, this event can occur for a variety of reasons, most having to do with errors in an email address.
You must set the Handled property of the object passed as the e parameter to true to signal that the exception has been handled; otherwise, the exception is thrown again.
Raising an event invokes the event handler through a delegate. For more information, see Server Event Handling in ASP.NET Web Forms Pages.
The method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.Notes to Inheritors
When overriding the method in a derived class, be sure to call the method for the base class so that registered delegates receive the event.