telnet to smtp . 421 4.3.2 Service not available Connection closed by foreign host

Question

When i try to telnet to a smtp server for port 25, i recieve "421 4.3.2 Service not available Connection closed by foreign host." I do have internet access on my linux system. Pls help.

Answer 1

A 421 error returned from a mail server means there is a problem with the mail server setup - this effectively says to the client "I have a problem and can't cope with email now, try again later" - with the expectation that the mail server configuration will be fixed soonish.

The 4.3.2 part of the message is something to do with Microsoft mail servers and gives a small hint into HOW the server is misconfigured, but its not very useful - see https://social.technet.microsoft.com/Forums/en-US/94c360f3-721c-46a0-9f8b-0d8386ccb0ba/telnet-fails-to-hub-transport-server-from-remote-sites?forum=exchangesvrsecuremessaginglegacy