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Lock Down Microsoft Exchange for Incoming SMTP Traffic

Customers using Microsoft Exchange can restrict incoming SMTP traffic so that email from The Email Laundry servers is accepted while all other SMTP traffic is rejected.

As customer’s MX records will be pointing to The Email Laundry servers,
no legitimate email coming from the internet will be sent directly to
the customer’s Exchange server.

Ideally, restricting incoming SMTP traffic is done at the firewall level before any traffic hits the server. However if the firewall does not allow this or indeed there is no firewall in place, the rules can be setup directly on the Exchange server.

Please note that if you allow any 3rd parties to relay through your Exchange server, these rules may prevent them from doing so.

Exchange 2003

Go to:

System manager > Administrative Groups > Server > Protocols > Expand SMTP

Right click on SMTP Virtual Server. Go to Access tab and then Connection.

Enter the IP addresses for The Email Laundry.

Restart the Virtual SMTP Server and SMTP Service.

Exchange 2007

Go to:

Exchange Management Console > Server Configuration > Hub
Transport > Receive Connectors tab > Default [mail server name]
> Properties > Network tab > Remote IP addresses section

Enter the IP addresses for The Email Laundry.
Add IP address range of local network so that local clients can connect into the server in order to send email.
Remove the existing 0.0.0.0-255.255.255.255 range.
Restart the Exchange Transport service.

in Email Security

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