With the Internet becoming mainstream and programmers wanting to communicate their applications over it, we've seen the need to know Windows sockets has become less important as the number of ActiveX and OCX controls rise. Still, there are things to know and there are things to learn about communicating over wide area networks.
Internet Mail is the most used mail protocol on the Internet. It includes sending mail, retrieving mail, and formatting the messages.
Windows Sockets
[>] AndreaVB
An excellent site with lots of information. The content ranges from low level programming using the Windows API, to ASP and COM components. You might get a bit lost in the design, but focusing on the center white section of the page will help a lot.
[>] Catalyst Software Corporation
Catalyst Software Corporation are the developers of SocketTools and the commonly known free-ware SocketWrench control. They have years of experience in developing Internet-Winsock controls, and are one of the most experienced companies on the market.
[>] Visual Basic 6.0 Internet Programming
[>] Visual Basic Internet Programming
VBIP specialises in Internet programming using Visual Basic. The site includes related books, tools / custom controls, tutorials, and sample applications.