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Mail Sending Settings.. Transactional Emails Not Sending.. Microsoft Exchange Server… Problem
We are running a magento store (1.6.0) on a linux server with email for the domain on a Microsoft Exchange Server. No transactional emails are getting to customers with the email address associated with the same domain, but are getting to accounts outside of the domain (hotmail and gmail, etc).
Try adding spf record to your dns, referencing the IP range of both the outgoing mail server and of the Magento installation server (it sends php mail through there).
This is something that is recommended regardless if it solves this particular issue or not, since it will help all receiving mail servers to accept your domain’s mail and not to filter it as spam.