Pivo SMTP Component   
http://www.pivo.com

Short for Simple Mail Transfer Protocol, a protocol for sending e-mail messages between servers. Most e-mail systems that send mail over the Internet use SMTP to send messages from one server 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. This is why you need to specify both the POP or IMAP server and the SMTP server when you configure your e-mail application. Pivo Smtp Component is one which can be used in web/window application like C#,ASP.NET, VB, smpt component allows your applications or web pages to create and send email messages over SMTP protocol just in a few lines of code. Sends messages as plain text or in the HTML format. Smtp Component can send email to any email address with or without smtp server as parameter. Email can contain any number of attachments, unlimited recipients, cc's and bcc's. Send Email directly from you web page via applications/browsers.

MailBee SMTP   
http://www.iforum.com

MailBee SMTP is a powerful and easy to use COM object which enables ASP and Windows applications to create, send and queue mail to SMTP servers. Secure authentication, email validation, correct MIME composer, multiple attachments, and much more. Can be used in conjunction with SSL, POP3 and IMAP4 components. Royalty-free distribution.