From various Outlook forums, the "target principal name" is the CN from the cert. So if Outlook is configured to hit mail.brazoslink.net but the CN is www.brazoslink.net (or brazoslink.net, as it is now), it's throwing a mismatch error. I can't find anyplace that Outlook ignores SANs, but that could be the issue; it doesn't surprise me at all when a Microsoft product doesn't exactly adhere to the standard.