SMTP SASL SASL AUTH NTLM SASL AUTH PLAIN SASL DOWNGRADE RFC4954 # Server-side AUTH NTLM PLAIN REPLY "AUTH NTLM" 334 NTLM supported REPLY %b64[NTLMSSP%00%01%00%00%00%06%82%08%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00]b64% 334 Rubbish REPLY * 501 AUTH exchange cancelled by client REPLY "AUTH PLAIN" 334 PLAIN supported REPLY %b64[%00user%00secret]b64% 235 Authenticated # Client-side smtp NTLM SSL !SSPI SMTP NTLM authentication with SASL downgrade mail body smtp://%HOSTIP:%SMTPPORT/%TESTNUMBER --mail-rcpt recipient@example.com --mail-from sender@example.com -u user:secret -T - # Verify data after the test has been "shot" EHLO %TESTNUMBER AUTH NTLM %b64[NTLMSSP%00%01%00%00%00%06%82%08%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00%00]b64% * AUTH PLAIN %b64[%00user%00secret]b64% MAIL FROM:%LTsender@example.com%GT RCPT TO:%LTrecipient@example.com%GT DATA QUIT mail body .