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i am trying to login to microsoft exchange online using openssl

openssl s_client -connect

however when i pass the USER command it fails

+OK The Microsoft Exchange POP3 service is ready.
-ERR Connection is closed. 12

any ideas on how to test this?

more research

i tried

nc -v 995
Connection to 995 port [tcp/pop3s] succeeded!


but no results...


openssl s_client -crlf -connect
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up vote 3 down vote accepted

You have to actually follow the POP3 protocol:

Commands ... consist of a case-insensitive keyword, possibly followed by one or more arguments. All commands are terminated by a CRLF pair. Keywords and arguments consist of printable ASCII characters. Keywords and arguments are each separated by a single SPACE character. Keywords are three or four characters long. Each argument may be up to 40 characters long.

Try passing -crlf to s_client.

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