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 Objects   
http://www.iforum.com

MailBee Objects is a set of poweful and easy-to-use COM objects sending, receiving and managing mail on SMTP, POP3 and IMAP4 servers. Smart and fast MIME parser, HTML mails, HTML mail safety (using MessageCensor component), ESMTP, SMTP queue, secure authentication, SSL/TLS (using SSL plugin), international charsets, email validation, multiple attachments, search for new/unread mails and mailbox management (IMAP4 only). Royalty-free distribution.

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.

MailBee SSL   
http://www.iforum.com

MailBee SSL component is a plugin which enables MailBee Objects (SMTP, POP3 and IMAP4) to communicate to mail servers over secure connections. Supports client and server certificates, custom stores, STARTTLS mode, and more. Requires just a few lines of code to completely turn existing application into secure one. Royalty-free distribution.

MailMill .NET Professional   
http://www.activeplus.com

MailMill .NET is a SMTP/MIME component 100% .NET Managed Code written in C# . It enables easy email creation and sending and lets you considerably speed up your development. Features: - Send HTML email with embedded images. - Send multipart/alternative emails with both HTML and plain-text bodies. - Send multiple file attachments. - Add any attachment formats from files or in-memory data. - Automatically encode contents using the most optimized transfer encoding mode. - Handle multi-language (including asian and arabic languages). - Support multiple To, CC, BCC and Reply-To. - Support standard and custom header fields. - Set the message priority. - SMTP and ESMTP protocols. - SMTP authentication (clear text). - Allow you to specify non standard SMTP port number. - Support Encryption and Digital Signature (S/MIME protocol). - Save your messages to the disk. - Include an email address validator to control email addresses. - Include an email address formatter to create email addresses with a display name in To, Cc, and From. - Compliance with RFC standards.