When you reply to a forwarded email, the sender should only see your alias, not your real email address (REA). With Reply Forwarding, e4ward changes your REA to the alias before the reply is delivered to the sender.
How it Works
Suppose Ann sends email to Bob at bobAlias1@bob.e4ward.com. Here's what appears in Bob's inbox:
From: ann*orig.com*bobAlias1*bob.e4ward.com*1607*7A44@reply.e4ward.com
To: bobAlias1@bob.e4ward.com
Notice the long address in the From field. This is an encoding of both Ann's address (ann*orig.com), and Bob's alias (bobAlias1*bob.e4ward.com), followed by some control fields and the domain reply.e4ward.com through which the reply will be routed.
When Bob hits reply this becomes:
From: bob@isp.com
To: ann*orig.com*bobAlias1*bob.e4ward.com*1607*7A44@reply.e4ward.com
Note that Bob's email client inserted bob@isp.com in the From. We don't want that transmitted to Ann! When Bob sends the message it will go through reply.e4ward.com where both the From and To will be rewritten so that this is what will appear in Ann's inbox:
From:bobAlias1@bob.e4ward.com
To: ann@orig.com
With Reply Forwarding, Ann and Bob can reply back and forth without Bob's real email address being displayed to Ann.