SMTP SASL SASL AUTH NTLM SASL AUTH PLAIN SASL DOWNGRADE RFC4954 # # Server-side AUTH NTLM PLAIN REPLY "AUTH NTLM" 334 NTLM supported REPLY TlRMTVNTUAABAAAABoIIAAAAAAAAAAAAAAAAAAAAAAA= 334 Rubbish REPLY * 501 AUTH exchange cancelled by client REPLY "AUTH PLAIN" 334 PLAIN supported REPLY AHVzZXIAc2VjcmV0 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 TlRMTVNTUAABAAAABoIIAAAAAAAAAAAAAAAAAAAAAAA= * AUTH PLAIN AHVzZXIAc2VjcmV0 MAIL FROM: RCPT TO: DATA QUIT mail body .