% perl -MMIME::Base64 -e 'print encode_base64("\000jms1\@jms1.net\000not.my.real.password")'
AGptczFAam1zMS5uZXQAbm90Lm15LnJlYWwucGFzc3dvcmQ=
% telnet 1.2.3.4 25
% telnet 1.2.3.4 25
220 a.mx.jms1.net NO UCE ESMTP
ehlo testing
250-a.mx.jms1.net NO UCE
250-STARTTLS
250-PIPELINING
250 8BITMIME
quit
220 a.mx.jms1.net NO UCE ESMTP
ehlo testing
250-a.mx.jms1.net NO UCE
250-AUTH LOGIN PLAIN
250-AUTH=LOGIN PLAIN
250-PIPELINING
250 8BITMIME
Assuming the server supports AUTH, we will send the actual AUTH command to try and authenticate.
AUTH PLAIN AGptczFAam1zMS5uZXQAbm90Lm15LnJlYWwucGFzc3dvcmQ=
mail from: <nospam@jms1.net>
250 ok
rcpt to: <nospam@jms1.net>
250 ok
data
354 go ahead
From: John <nospam@jms1.net>
To: Nobody <nospam@jms1.net>
Subject: fnord
hail eris!
.
250 ok 1113954693 qp 29052
quit
221 a.mx.jms1.net NO UCE