smtp service

perl -MMIME::Base64 -e 'print encode_base64("\000username\@your-domain-name.com\000password-here")'

openssl s_client -starttls smtp -crlf -connect mail.domain.com:587

[or]

openssl s_client -crlf -connect mail.domain.com:465

#------------------------------
ehlo testing
auth plain {encoded-text-from-base64}
mail from: <user@domain.com>
rcpt to: <someone@other.com>
data
from: blabla <user@domain.com>
to: jdoe <someone@other.com>
subject: testing

{this is body part}

.
#-------------------------------