SMTP via openssl an Exchange Server

generate User and Password Hashes

echo -n 'username or password' | openssl base64

openssl s_client -connect mail.example.com:465 -starttls smtp -crlf -ignore_unexpected_eof

EHLO mail.example.com

AUTH LOGIN

<username hash>

<password hash>

MAIL FROM:<info@example.com>

rcpt to:<rcpt@example.com>

DATA
Subject: An intresting subject

Some random Email content

.
QUIT

caveats: - Password hash should not start with a "R": https://www.openssl.org/docs/man3.0/man1/openssl-s_client.html R: Renegotiate the SSL session (TLSv1.2 and below only).