SMTP SASL SASL AUTH LOGIN SASL-IR RFC4954 # Server-side AUTH LOGIN REPLY AUTH 334 %b64[Password:]b64% REPLY %b64[secret]b64% 235 Authenticated # Client-side smtp SMTP login authentication with initial response mail body smtp://%HOSTIP:%SMTPPORT/%TESTNUMBER --mail-rcpt recipient@example.com --mail-from sender@example.com -u user:secret --sasl-ir -T - # Verify data after the test has been "shot" EHLO %TESTNUMBER AUTH LOGIN %b64[user]b64% %b64[secret]b64% MAIL FROM:%LTsender@example.com%GT RCPT TO:%LTrecipient@example.com%GT DATA QUIT mail body .