Dell 2335dn scan submission to remote Exchange Server

We're trying to configure our Dell 2335dn to submit scans to a remote Exchange Server via authentication. The manual doesn't seem to have much beyond setting it up. The most progress we can see is the scanner attempts the connection, but then it immediately disconnects. Below is a sample communication. It appears the scanner is immediately quitting the session without even trying. We've tried connections on ports 25 and 465 and any number of Exchange Receive Connector changes. What kind of "authentication" setup is the Scanner expecting to get from the server? *,SMTPSubmit SMTPAcceptAnySender SMTPAcceptAuthoritativeDomainSender AcceptRoutingHeaders,Set Session Permissions 220 ExchangeServer.Mycompany.com Microsoft ESMTP MAIL Service ready at Tue, 18 Feb 2014 13:47:07 -0600", EHLO DEL001599DE6A61, 250-ExchangeServer.Mycompany.com Hello [ScannerRemoteIP], 250-SIZE, 250-PIPELINING, 250-DSN, 250-ENHANCEDSTATUSCODES, 250-STARTTLS, 250-X-ANONYMOUSTLS, 250-AUTH NTLM, 250-X-EXPS GSSAPI NTLM, 250-8BITMIME, 250-BINARYMIME, 250-CHUNKING, 250-XEXCH50, 250-XRDST, 250 XSHADOW, QUIT, 221 2.0.0 Service closing transmission channel,