Your domain cannot accept email from a Foreign Domain as a Proxy for that domain.
You cannot create a foreign mail store on your domain for another domain that you do not have ownership of..
How to Set Up a Proxy Email
How to Set Up a Proxy Email
Microsoft Outlook 2003
Open the program and click "Tools." Select "E-Mail Accounts" and click "View or Change Existing E-Mail Accounts Options." Click "Next." Highlight the e-mail account types that have already been configured. Click "Change." This brings up the "Internet E-Mail Settings" dialog box.
Click "More Settings" and select the "Outgoing Server" tab. Set the "Outgoing Server" as "smtp-proxy.tm.net.my." Uncheck the "My Outgoing Server (SMTP) Requires Authentication" box.
Click the "Advanced" tab and enter "Port 25" under "Outgoing Server (SMTP)." Click "OK," "Next" and "Finish."
Now don't you feel stupid?