SMTP SASL SASL AUTH PLAIN SASL-IR RFC4616 RFC4954 # Server-side AUTH PLAIN REPLY AUTH 235 Authenticated # Client-side smtp SMTP plain 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 PLAIN %b64[%00user%00secret]b64% MAIL FROM:%LTsender@example.com%GT RCPT TO:%LTrecipient@example.com%GT DATA QUIT mail body .