Emailserver detector   
http://www.worldminer.com

Emailserver detector is a software designed to directly search email addresses from mail servers. It can verify all user names that you specified on the mail server.The program tries to connect with a specail Smtp-server and simulates sending the message. It does not come to the message sending ,in fact,It disconnect as soon as mail server informs does this address exist or not.The program is multi-threaded that provides the high speed of verifying. Using this software, you can get lots of email addresses from a special email server,For example :Hotmail.com .It can also send message to valid email addresses while searching.It has Embeded in a SMTP server that quickly send mass email directly to recipients.No use your ISP'S SMTP server.You can also save the valid email addresses to a one-per line text file.

X-Ray Mail Assistant Beta   
http://www.xrayapp.com

X-Ray is an email header filter and POP/SMTP server switching tool. It runs as a local POP/SMTP relay server and scans your incoming and/or outgoing mail for user specified mail headers. Once it finds a match it can change the header, remove it, replace it or perform some other special modifications. In addition, the program allows you to set up multiple profiles for POP and SMTP servers and switch between them from the system tray. X-Ray can also run as an NT service.

X-Ray Mail Assistant   
http://www.xrayapp.com

X-Ray is an email header filter and POP/SMTP server switching tool. It runs as a local POP/SMTP relay server and scans your incoming and/or outgoing mail for user specified mail headers. Once it finds a match it can change the header, remove it, replace it or perform some other special modifications. In addition, the program allows you to set up multiple profiles for POP and SMTP servers and switch between them from the system tray. X-Ray can also run as an NT service.

SPAMfighter SMTP Anti Spam Server   
http://www.spamfighter.com

SPAMfighter SMTP Anti Spam Server, is the easy-to-use anti-spam solution for Microsoft Windows Servers. SPAMfighter SMTP Anti Spam Server is powered by the SPAMfighter Server, which is updated by the SPAMfighter community of more than 1.2 million users across the globe. SPAMfighter SMTP Anti Spam Server delivers instant spam protection with no configuration or maintenance what so ever. As email arrives and the SMTP Server routes it to its addressees, SPAMfighter constructs a unique signature for each message and sends it to the SPAMfighter Server for evaluation. If the SPAMfighter Server determines that a message is spam, it filters the mail before it is moved to the user's spam folder.

wodSmtpServer   
http://www.weonlydo.com

WeOnlyDo! SmtpServer ActiveX control is a component that can be easily integrated into your applications to provide full non-relaying Smtp (Simple Mail Transfer Protocol) server implementation. All you need to do is to put it on VB form, call it's Start method and it's immediately accepting connections by your clients! It fully supports commands defined in RFC2821. Use your favorite mail client (such as Outlook Express or Eudora) to send mail to other users on your network . How? That's easy part: just put SmtpServer control on your form, add some code around and it's all setup to be used. If you dislike adding additional code - it's fine by Smtp. It will still work, and accept all emails but delete them immediately after user disconnects. But, if you define real filename on your disk, all the emails will be stored to that file. Still, if you want to make real Smtp server application, look no more for native support for socket related material - you just found it. Smtp server will deal with clients and connections - you must deal with messages. Once new user connects to your Smtp server, you need to provide some way of storing message posted by user to some file on disk, or just read it from Body property and store manually to, for example, database. This is really easy task. If you keep all the emails in separate files, that's just great for usage with WeOnlyDo! Smtp server. If you prefer to keep it in one large file - we will not argue about it. You can specify filename, make Smtp server Append to that file, and everything will still work just great. As a result, you will have one mailbox for each user just like on UNIX computers. Together with WeOnlyDo! Pop3 server, you can make powerful fully maintained mail service application that will share emails in your company, receive them from internet and anything else you can imagine. You can even create emails for your employees on the fly. You can make Smtp store to same files from where Pop3 reads them.