As with any proxy, eWall shares one common disadvantage: the email senders SMTP servers IP address will be hidden behind eWall. This may be good in the case of web proxy, that hides the originating web surfers IP address and thereby provides some privacy, but in the case of a mail server is less than optimal. As a result, your mail server may lose the ability to utilize it's IP based protection mechanisms, as the mail server will always see the eWall's IP address (Fig.1), and as a result all arriving emails always have eWall's IP address in their header.
Fortunately, we have developed a unique Transparency Module (EWLSP) , that can be used to get around this limitation. EWLSP stands for eWall Layered Service Provider (more information about Layered Service Providers can be found here). This is an optional plugin, that transfers the originating senders IP address directly to the mail server application to re-enable the usage of your mail servers IP address based utilities.
Although EWLSP is well-tested and stable, it may not work under all circumstances: