SMTP SASL SASL AUTH CRAM-MD5 RFC2195 RFC4954 # Server-side AUTH CRAM-MD5 REPLY AUTH 334 %b64[%3c1972.987654321@curl%3e]b64% REPLY %b64[user 7031725599fdbb5d412689aa323e3e0b]b64% 235 Authenticated # Client-side smtp crypto digest SMTP CRAM-MD5 authentication mail body smtp://%HOSTIP:%SMTPPORT/%TESTNUMBER --mail-rcpt recipient@example.com --mail-from sender@example.com -u user:secret -T - # Verify data after the test has been "shot" EHLO %TESTNUMBER AUTH CRAM-MD5 %b64[user 7031725599fdbb5d412689aa323e3e0b]b64% MAIL FROM:%LTsender@example.com%GT RCPT TO:%LTrecipient@example.com%GT DATA QUIT mail body .