SMTP SASL SASL AUTH PLAIN RFC4616 RFC4954 # Server-side AUTH PLAIN REPLY AUTH 334 PLAIN supported REPLY %b64[ursel%00kurt%00xipj3plmq]b64% 235 Authenticated # Client-side smtp SMTP plain authentication with alternative authorization identity mail body smtp://%HOSTIP:%SMTPPORT/%TESTNUMBER --mail-rcpt recipient@example.com --mail-from sender@example.com -u kurt:xipj3plmq --sasl-authzid ursel -T - # Verify data after the test has been "shot" EHLO %TESTNUMBER AUTH PLAIN %b64[ursel%00kurt%00xipj3plmq]b64% MAIL FROM:%LTsender@example.com%GT RCPT TO:%LTrecipient@example.com%GT DATA QUIT mail body .