The first requirement for the Cron Piping Method on http://docs.whmcs.com/Email_Piping states, “On your mail server create a unique email account for each support department. This must be a full inbox, an alias is not sufficient.” Although true, this might lead you to believe that an email alias cannot be used to pipe emails. The solution is to create a full inbox for each which is what we did in Part 1.
If you created a subdomain under the same support department root domain, we can now create the forwarders to mask the subdomain.
Step 1 – Create aliases
1. Login to your Google Apps Gmail account with your Administrator account.
2. Access the Admin console by clicking the wrench button in the top-right corner and select “Manage this domain”.
Alternatively you can visit https://admin.google.com directly.
3. Click on the name of a user.
4. Click “Account”.
5. Scroll down and click “Add an alias”. Enter a WHMCS support department username.
6. Repeat for all departments.
Step 2 – Add forwarding addresses and create filters
1. Go back to Gmail. Click the wrench button in the top-right corner and select “Settings”.
2. Click “Forwarding and POP/IMAP” tab.
3. Click “Add a forwarding address” button. Enter full inbox address with subdomain. e.g., email@example.com
4. Repeat for all departments.
5. Click “Filters” tab.
6. Click “Create a new filter”.
7. Enter masked address into the “To” field. e.g., firstname.lastname@example.org
8. Click “Create filter with this search”.
9. Check “Forward it to:” and select corresponding forwarding address.
10. Repeat for all departments.
Thanks to SajanP for his comments at WHT.
Add or remove an email alias address for a Google Apps user (Google Apps Admin Help)
Forwarding options (Google Apps Admin Help)
Using filters (Google Apps Admin Help)