11.3 All Mail from the Hub

Recall that one purpose of client.cf is to make all messages appear to originate from the hub. The purpose of a rule set Hubset is to rewrite the sender's address so that the mail message always appears to originate from the hub machine.

From: user@client         

       
becomes
         

 From: user@hub

This could be done by rule set 3, but that would affect all addresses, both recipient and sender, which is not appropriate. Mail should not appear to be both to and from the hub, but should appear to be only from the hub. It could also be done in rule set 1 (which we will cover soon), but that would affect all sender addresses. You don't want to rewrite all sender addresses, just those that are being sent through the hub. You may someday want to use prog or local delivery agents, and the sender's address should be left unchanged for them.