Our setup is this.  Exchange 2013, GFI Faxmaker 2015 using the SR140 FOIP, all going out through a Audiocodes Mediant 1000.  We also have multiple HP MFP's that are able to send faxes out w/o any issues, we can also receive faxes with no problems.  Our issue is when we sent the fax trough the mail client (outlook 2013)  Analyzing all of the logs, we see that when the email goes out, the from header has only the phone number, example: <sip:55555555>  the working SIP call has a valid URI, the failing one is missing the standard SIP URI format 5555555@domain.com.  Does anyone have any thoughts on how we can possibly manipulate the from header when sent from email to put it in the correct format?  Thanks.