Watchguard Firebox X1000 User Manual page 170

Chapter 9: Configuring Proxied Services
inside.salesdept.bigcompany.com, which would become the
public address bigcompany.com .
1
Click the Masquerading tab.
The SMTP masquerading information appears, as shown in the
following figure.
2
Enter the official domain name.
This is the name you want visible to the outside world.
3
In the Substitute the above for these address patterns
text box (to the left of the Add button), type the address
patterns that are behind your firewall that you want
replaced by the official domain name. Click Add.
All patterns entered here appear as the official domain name
outside the Firebox.
4 In the Don't Substitute for these address patterns text
box (to the left of the Add button), type the address
patterns that you want to appear "as is" outside the
firewall. Click Add.
5
Select the checkbox marked Masquerade Message IDs
to specify that message IDs in the Message-ID and
Resent-Message-ID header fields are converted to a
new ID composed of an encoded version of the original
ID, a time stamp, and the host name entered in the
domain name field described in step 2.
148 WatchGuard Firebox System