That's right DIGEST-MD5, your job is done here. Now it's time for the new kid to take up your place.

Those of you who ever tried to actually implement the DIGEST-MD5 SASL mechanism for authentication know that it suffers from quite a few problems, including but not limited to a variety of different implementations with a variable level of compliance to the DIGEST-MD5 RFC 2831. These interoperability problems make it quite hard to get a new implementation working with most of the already existing implementations.

SASL mechanisms are designed to be protocol-independent. That's basically the whole idea about SASL; to abstract the authentication part out of the application protocols, and standardize it. However DIGEST-MD5 already started off on the wrong foot.