No connection with server with Telnet

[MaartenRo]

Hi,

I am reading a book about networking. It says that i should use Telnet to carry out a direct dialogue with an SMTP server by issueing "telnet serverName 25" in the Windows command prompt. When i do this i get the message that there is a connection being made within serverName....Fails to connect to host on port 25: faied to connect (translated from dutch). What am i doing wrong?

 

[beers]

From where to where? If the destination doesn’t support tcp25 then no connecto

 

[MaartenRo]

Thank you for your reply, i am totally new to this. But how do i know what destination is supported and what port i can use?

 

[voyagerfan99]

Thank you for your reply, i am totally new to this. But how do i know what destination is supported and what port i can use?

If it fails to connect then that means port 25 is not open

For example you can do something public like telnet smtp.office365.com 25 and it will open a connection

 

[beers]

Thank you for your reply, i am totally new to this. But how do i know what destination is supported and what port i can use?

You can derive the mail server for whatever domain you want by querying the MX records for it in DNS.

It's up to whoever runs it if they accept standard SMTP.