Telnet is a more advanced utility used to determine if certain ports are open or reachable. You would use the telnet utility in the event you want to make sure you have access and are not being blocked through a local issue such as a firewall.
When you connect to our mail servers to send or receive emails you will utilise different ports on your local machine to connect to the remote destination.
TELNET ON WINDOWS MACHINES
(some versions of windows does not have telnet utility installed as standard so you might need to install it)
1. Go to Start > Run
2. Type one of the commands below
To determine POP access
normal pop: TELNET POP.EMAILSRVR.COM 110
secure pop: TELNET SECURE.EMAILSRVR.COM 995
To determine IMAP access
normal imap: TELNET IMAP.EMAILSRVR.COM 143
secure imap: TELNET SECURE.EMAILSRVR.COM 993
To determine SMTP access
normal smtp: TELNET SMTP.EMAILSRVR.COM 25 (or use ports 587, 8025, or 2525)
secure smtp: TELNET SECURE.EMAILSRVR.COM 465
You will then see a black dos box popup as below which will give you an ok message.
if the dos box hangs, then its possible that your ports on your computer firewall or your routers firewall are not open thereofre you will need to contact the administrator for your network.
NOTE: Some isp's are known to block port 25 so if you have issues then try ports 587, 8025 or 2525.