I'm trying to telnet to imap-mail.outlook.com on port 993. When I connect to it, I get

Connected to imap-mail.outlook.com.  
Escape character is '^]'.

And I can enter a command. Whenever I enter seemingly anything, it disconnects me saying:

Connection closed by foreign host.

I'm trying to determine (or even venture a guess as to) the reason and I don't know enough about telnet to even make an educated guess. Can anyone point me in the right direction?

For the record, I'm able to connect a desktop mail client to this address and it works fine. The machine I'm trying from is on the same network running CentOS 6 with no firewall rules whatsoever, which clearly isn't the problem anyway.

  • What commands did you try to enter? Have you compared that with what your software sends? The most obvious reason would be that you entered an invalid command, and you've given us no reason to rule that out. Commented Nov 19, 2014 at 1:09

1 Answer 1


The host probably expects SSL. You must use openssl instead of telnet:

openssl s_client -connect imap-mail.outlook.com:993 -crlf
  • Understood. I did that and I get: openssl s_client -connect imap-mail.outlook.com:993 -quiet ........... * OK Outlook.com IMAP4rev1 server version ready (DUB451-IMAP27) After getting that prompt, I type LOGIN username password and eventually I get a read error and it DCs.
    – JamesB41
    Commented Nov 19, 2014 at 0:20
  • @JamesB41 Does it work with -crlf? Commented Nov 19, 2014 at 0:36
  • Ah-ha. I got there on my own after an hour or two. -crlf was a piece of the puzzle. I was also just doing LOGIN <user> <pass> when I needed to prefix it with a ?. Thanks for the help, I'll accept your answer.
    – JamesB41
    Commented Nov 19, 2014 at 1:36

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