How to force Forefront (FOPE) to use North American data centers to route email
If you use Microsoft’s hosted Forefront service, sometimes your outgoing email may appear to originate from a different geographic location than your source email server. This is because Microsoft load balances across all of its worldwide datacenters when filtering email through FOPE.
Some organizations decide to block all email originating from some geographic locations. i know of at least one State of Florida government department that does not accept email that appears to originate from the UK.
If you use FOPE and want all of your emails to orginate from North American data centers change your email server’s smarthost to from mail.global.frontbridge.com to mail.us.messaging.microsoft.com.