EHLO
250-exchange Hello []
250-SIZE 36700160
250-PIPELINING
250-DSN
250-ENHANCEDSTATUSCODES
250-AUTH NTLM LOGIN
250-8BITMIME
250-BINARYMIME
250 CHUNKING
AUTH LOGIN
334 VXNlcm5hbWU6
dXNlcm5hbWU=
334 UGFzc3dvcmQ6
cGFzc3dvcmQ=
235 2.7.0 Authentication successful
MAIL FROM:<username@mydomain.com>
250 2.1.0 Sender OK
RCPT TO:<recipient@somewhereelse.com>
250 2.1.5 Recipient OK
DATA
354 Start mail input; end with <CRLF>.<CRLF>
SUBJECT: Test Email
Hello

.
550 5.7.1 Client does not have permissions to send as this sender