SMTP SASL SASL AUTH DIGEST-MD5 RFC2831 RFC4954 # Server-side AUTH DIGEST-MD5 REPLY AUTH 334 %b64[realm="cu\"rl",nonce="5300d17a1d695bd411e4cdf96f9548c23ced6175",algorithm=md5-sess,qop="auth"]b64% REPLY %b64[username="us\"er",realm="cu\"rl",nonce="5300d17a1d695bd411e4cdf96f9548c23ced6175",cnonce="34333231353332313633323137333231",nc="00000001",digest-uri="smtp/127.0.0.1",response=53d3347e1b559d23be78934ae4a78488,qop=auth]b64% 334 %b64[rspauth=9ea859cb9d90c37ca30d49d35378630c]b64% REPLY 235 Authenticated # Client-side smtp !SSPI Debug crypto digest CURL_ENTROPY=12345678 SMTP DIGEST-MD5 authentication mail body smtp://%HOSTIP:%SMTPPORT/%TESTNUMBER --mail-rcpt recipient@example.com --mail-from sender@example.com -u "us\"er:secret" -T - # Verify data after the test has been "shot" EHLO %TESTNUMBER AUTH DIGEST-MD5 %b64[username="us\"er",realm="cu\"rl",nonce="5300d17a1d695bd411e4cdf96f9548c23ced6175",cnonce="34333231353332313633323137333231",nc="00000001",digest-uri="smtp/127.0.0.1",response=53d3347e1b559d23be78934ae4a78488,qop=auth]b64% MAIL FROM:%LTsender@example.com%GT RCPT TO:%LTrecipient@example.com%GT DATA QUIT mail body .