Question : How do I change the IP address in my outgoing email message headers?

Here's the issue:

All outgoing data from our organization is passed through the firewall.  Essentially, the mail server is XX.XXX.XXX.134 (this is for O.W.A.) but the message headers have XX.XXX.XXX.5 as the IP address that it's from.  The .5 IP address is the external IP of our firewall.

This is a huge issue because we've ended up on SORBS dns list because it thinks we have a dynamic IP address.

Answer : How do I change the IP address in my outgoing email message headers?

I believe the SonicWall Pro 4060 only comes with the Enhanced software?   Not standard?

Just create a NAT:

Click on Network -->  NAT Policies -->  Select Public Server Wizard button in the top left.
Wizard opens Click Next,
Step 1: Select Mail Server as type, and de-select and protocols not needed, click next
Step 2: Server name:  put in whatever discription, then the private IP, Click next
Step 3:  Public server IP:  this is the IP you want your message headers to be..., click Next and apply

I would remove all the OLD rules and NAT's for the Exchange server so nothing gets confused.   Best way to do this is under Nat Policies click view style:  Custom Policies and remove all the old Exchange rules.   You can do this before you run the NAT Policy wizard, but your mail flow will be down for the minute it takes you to run the wizard.

I would do the same thing under  Firewall Access...remove all the old exchange rules for SMTP...

Or to be safe you can uncheck them under Enable to just disable then once you have it working just delete.