SMTP SMTP AUTH LOGIN SASL-IR RFC4954 # # Server-side REPLY EHLO 250 AUTH LOGIN REPLY AUTH 334 UGFzc3dvcmQ6 REPLY MTIzNA== 235 Authenticated # # Client-side smtp SMTP login authentication with initial response mail body smtp://%HOSTIP:%SMTPPORT/user --mail-rcpt 908@foo --mail-from 908@from -u test:1234 -T --sasl-ir - # # Verify data after the test has been "shot" EHLO user AUTH LOGIN dGVzdA== MTIzNA== MAIL FROM:<908@from> RCPT TO:<908@foo> DATA QUIT mail body .