SMTP SMTP 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/user --mail-rcpt 907@example.com --mail-from 907@example.com -u test:1234 --sasl-ir -T - # # Verify data after the test has been "shot" EHLO user AUTH PLAIN dGVzdAB0ZXN0ADEyMzQ= MAIL FROM:<907@example.com> RCPT TO:<907@example.com> DATA QUIT mail body .