SMTP SMTP AUTH PLAIN RFC4616 RFC4954 # # Server-side REPLY EHLO 220 AUTH PLAIN REPLY AUTH 235 Authenticated # # Client-side smtp SMTP plain authentication mail body smtp://%HOSTIP:%SMTPPORT/user --mail-rcpt 805@foo --mail-from 805@from -u test:1234 -T - # # Verify data after the test has been "shot" EHLO user AUTH PLAIN dGVzdAB0ZXN0ADEyMzQ= MAIL FROM:<805@from> RCPT TO:<805@foo> DATA QUIT mail body .