This brief section explains how to telnet into your email account and check your messages. This information is taken from rfc 1801 on the POP 3 protocol. It also shows you how send mail by telnetting into your SMTP server and composing your messages there.
Checking your email via direct telnet to your POP server
One overlooked but useful practice is how to telnet into your pop server and check your email. This is useful in that many times you may find yourself at a different terminal from your main computer and do not have the email set up so that you can check your messages. With this howto you can log into any mail server from a linux or windows box and check your mail without downloading it. Here it goes:
In linux at a prompt type telnet. Next type open mail.yourisp.com 110 or whatever your email server is. The 110 is the port of your server and should be universal. You will be greeted at a prompt with little or no help available. Now type user johndoe or you pop logon name. Now type pass xxxx where xxxxx represents your password. You should get o.k.'s after each entry. Now type list. You might see something like this:
To view a message type top 1 10 to display the first 10 lines of your first message. Type top 1 50 and likely your entire messages will scroll by. By typing 10 you will likely get the message headers and the author subject, and maybe some of the message body. Type top 2 10 for your second message. To delete a message type dele 1 or 2 for the first or second message. You can then just quit the session and now you know what's waiting for you the next time you launch your full email client. This is great like I said if your on the road and need your isp's email.
In windows fire up the telnet client by typing telnet at start->run . Now edit preferences so that local echo is enabled. Now connect and specify port 110 in the dialog box and follow the above steps.
Sending email by telnetting directly to your SMTP server
Well now that you can telnet to your POP server how about sending email. For that you must telnet directly to your ISP's SMTP server. At a terminal type telnet mailserver.madeup.net 25 with your actual mailserver address instead of madeup.net. Now you need to introduce yourself so type Helo johndoe where johndoe is your email name. Now type Mail From:yourname then type RCPT to:whoyoursending to then type Data . Now type your message. when your done put a . on a blank line and the message will be sent. That's it have fun.