For MailShark to safeguard Inbound email, MX records need to be directed to MailShark inbound servers.


For MailShark to safeguard outbound email, SMTP AUTH needs to be used on MailShark outbound relay servers.


Ideally for Inbound mail, MailShark would deliver clean mail to another mail server hosting mailboxes.


Ideally for Outbound mail, MailShark would receive outbound mail from another server hosting mailboxes using the SMART HOST configuration of that mail server.


In Detail


For inbound email, the MailShark Email Filter solution acts as a Mail Relay only, it does not host mailboxes.


When MailShark delivers clean email to a destination mail server, users would POP, IMAP, MAPI their email from that server.


For outbound email, there are 2 options:

  1. users can use the mail server hosting the mail boxes for outbound relay, then that server relays emails to MailShark for filtering and managed delivery aka use MailShark's outbound relay as a Smart Host from that server.

  2. users can use MailShark outbound relay directly

For security reasons, we would highly recommend option 1, as the mail server hosting the mail boxes will be able to better manage mail flow from machines to a single point (itself) and allow only devices allowed to relay through itself.


Option 1 allows the blocking of all port 25 outbound traffic from business networks, only allowing it through the mail server hosting the mail boxes.


Option 1 also allows the view of any devices that are infected with viruses, malware or are part of a botnet by checking port 25 outbound connections from the device to the server hosting the mail boxes.


If opting for option 2 and one device within a business network becomes infected with viruses, malware or are part of a botnet, MailShark will take automatic "blocking" actions on source IP's to stop a spam outbreak to the internet world, which will affect the outbound mail delivery of other devices that are not infected.