Guides

Here are a few of the guides I've made based on items that I've had to troubleshoot over the years.
I hope they are of some use to you...

SMTP Interactive Testing
How to send an Email interractively using telnet. Covers the basics of sending Email to check a server and also how to check the Auth Login feature of SMTP.
POP3 Interactive Testing
How to check Email using POP3 interractively with telnet. Includes using basic authentication and the APOP protocol.
IMAP Interactive Testing
How to check Email using IMAP interractively with telnet. Includes using basic authentication and Auth IMAP protocol.
HTTP Interactive Testing
How to use telnet to check if a Web server is working. Covers both IP and Name based virtual hosting.