For some reason, Microsoft’s default configuration for Exchange 2007 and 2010 exposes the internal server name in the mail headers, which causes most reverse-record-checking sites to bounce your email.

##EXCHANGE 2007##
To address this issue, you must remove the “NT AUTHORITYAnonymous Logon”? permissions from the send connector. Open the Exchange Management Shell, and do this:
>get-sendconnector (this will show the name of the send connector.)
SEND CONNECTOR NAME

>get-sendconnector <send CONNECTOR NAME>? | Remove-ADPermission -AccessRight ExtendedRight -ExtendedRights ms-Exch-Send-Headers-Routing? -user "NT AUTHORITYAnonymous Logon"

## EXCHANGE 2010##
1. Go to Exchange Management Console
2. Under Organization Configuration, select Hub Transport
3. Select Transport Rules, then “New Transport Rule”
Give the Rule a name, then set the following:

Conditions: Sent to Users Outside the organization
Remove Header: Received
Exceptions: None