Telnet - SMTP, POP3, IMAP4 and Others.

Hi friends

This article explains the importance of telnet command while troubleshooting connectivity in term some port numbers open close status and also more options in email protocols. The telnet plays fine role in finding the port status while troubleshooting email issues and also other applications.

General Port Status finding:

Syntax :

telnet {IP address | FQDN} {Port number}

Suppose to find whether remote desktop is enables in remote computer, the syntax will be

telnet hostname 3389

If it shows a blank windows, the RDP is enabled and else cases it through errors.


TELNET SMTP:

telnet severname 25
Helo
Mail from : administrator@domain.com
Rcpt to : someclient@domain.com
Data
{type the message} .{enter twice}
quit

TELNET POP3:

telnet servername 110
User userid@domain.com
Pass {password}
Stat
List
Quit

TELNET IMAP4:

telnet servername 143
? login userid@domain.com {password}
? list “” “*”
? select {foldername} (foldername=inbox,outbox,sent items,etc)
? fetch {msg number} all (msg number=1,2,3,etc)
? fetch {msg number} body (msg number=1,2,3,etc)
? logout

Thanks
Logu
logu_microsoft@hotmail.com
91-98414-99143