Simple Mail Transfer Protocol:
Short for Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers. Most e-mail that send mail over the Internet use SMTP to send messages from one to another; the messages can then be retrieved with an e-mail client using either POP or IMAP. In addition, SMTP is generally used to send messages from a mail client to a mail server.
Reasons why you might want to send email from your Web application:
create a “give us your feedback” Web page
implement a “forgotten password” script that sends a password to the user’s email account
send an automatic welcome email to your new newsletter subscriber
send automatic email update notifications
send automatic email notifications whenever an error occurs in your Web application
A relay is a service that allows you to send email. It is usually a full fledged mail server, or can be a specialized SMTP Service. Some examples of a mail server include Microsoft Exchange, IMail by IPSwitch, or Mail Enable by Mail Enable. An example of a SMTP service is the SMTP Service installed that can be installed with IIS. SNM sends email to a relay server, and the relay server is responsible for delivering the email to the final destination. When sending email to a relay server, you must have protocol permissions to use that server. Because of SPAM problems, relay servers are normally locked down, either by IPAddress or by some type of username/password authentication. Relaying errors are the most common problems when programmatically sending emails.
System. Net. Mail Namespace:
System.Net.Mail is the namespace used to send email if you are using the 2.0 (or higher) .NET Framework.
Unlike System.Web.Mail, which was introduced in the 1.0 Framework, it is not built upon the CDO/CDOSYS libraries. Although some functionality has been removed, the new System.Net.Mail namespace is much more versatile than the older CDO dependant System.Web.Mail.
In this Mail Namespace, the following classes are available
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