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.