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/919 --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 919 AUTH PLAIN dXNlcgB1c2VyAHNlY3JldA== MAIL FROM: RCPT TO: DATA QUIT mail body .