EDIT: Blekh, i dont know why i missed your second post ><. Disregard what i said in this post.
Hi Mir,
I've worked on a bunch of protocols in my time using Java. I can guide you in the right direction but you have to choose your own path.
I'm assuming the mailbox is located on a pop3 server.
Simplest possible way of doing it, get what the others have done:
http://www.google.com/search?hl=en&q=pop3+vb.net+example&btnG=Search
Longer manual solution:
However if you're interested in hacking your way through, start off by opening up a telnet session and connecting to the mail server:
> telnet my.mailserver.com 110 # 110 is the default pop3 port, its hardly ever changed.
USER yourusername # Send the server your username
PASS yourpassword # Your password
LIST # this will list the emails (i think unread only) you have
RETR [NUMBER] #Retrieve message(header i think)based on number through LIST command.IE: RETR 5
You can find additional information on POP3 in RFC1939, use
http://www.rfc-editor.org/ or any RFC website to get information on the rfc.
After you're comfortable with pop3 commands, open up a library in vb and create a class that would communicate with the server and send the proper commands based on the server response (all listed in the RFC).
Note that your application *must* be threaded as you do not wish to hold your parent process while waiting for the server response.
Not sure how much this helps, but if you need any further information, dont hesitate to ask.