Telnet - SMTP
To test a POP3 connection using telnet open a command window or shell terminal and type the following
telnet smtp.domain.com 25
Where smtp.domain.com is the FQDN (Fully Qualified Domain Name) or IP address of the server you wish to test.
25 also assumes default SMTP configuration.
You will be greeted with something similar to:
Escape character is '^]'. 220 smtp.domain.com
Now you need to enter the HELO command, followed by an idenfication of the server you ar esending from.
HELO buzz.domain.com 250 smtp.domain.com
Anything other than “250” indicates a problem.
You can now proceed with the test email transaction.
MAIL FROM: firstname.lastname@example.org 250 Ok RCPT TO: email@example.com 250 Ok DATA 354 End data with <CR><LF>.<CR><LF> This is where the data goes, you finish the input by placeing a dot (.) on a single line. . 250 Ok: queued as D9FA03705C9 QUIT 221 Bye Connection closed by foreign host.