E-mail Authentication errors

[Too_Tall_Crown_Victoria]

I have been using Visual Build for 2 years now. In the scripts we use if there is a failure we send an e-mail. Up to now there have been no problems with this feature. This is the error I am getting now:

Error authenticating user: User authentication failed (5.7.3 Authentication unsuccessful )

For the server we have always has "localhost". Even if I change it to the ip of the mail server I get this error:

Error authenticating user: Server does not support this option (splkexch1.spanlink.com Hello [192.168.252.14] TURN ATRN SIZE ETRN PIPELINING DSN ENHANCEDSTATUSCODES 8bitmime BINARYMIME CHUNKING VRFY X-EXPS GSSAPI NTLM AUTH GSSAPI NTLM X-LINK2STATE XEXCH50 OK )

I can send e-mail just find using outlook. Our MIS dept. can't find anything wrong on the server.

Any ideas?