I have a problem regarding Telnet when used as debugging tool
Considering that you connect to a mail server on port 25 using the following command
telnet mail.mailer.com 25
The mailer will reply and expect you to return smtp commands. Now my problem is the following. How thus the initial handshaking take place. Reasoning it out I understand that the mail server has to be able to do the telnet handshaking and establish aconnection before actually being able to accept smtp messages.
So is the mailer able to understand both smtp commands and telnet commands the latter in order to set up the connection
The telnet handshaking is essentially just setting up a tcp connection. After that it simply passes characters around as it gets them.
I have been told that there are telnet commands which I expect would upset the smtp server, but I have never encountered them myself.
Telnet is very simple, the heavy lifting of logins and whatnot are handled by processes on the server.
Does that help?