Autodiscover Returning Internal FQDN for Mail Server

Hi, everyone!

We recently updated our Autodiscover method after realizing we were relying on an outdated method. We created the proper autodiscover CNAME and SRV records in DNS and installed an updated SSL based on those name.

Something a bit unexpected has started happening now. Outlook has begun automatically updating everyone's mail server address to our internal FQDN, not the external one.

This has caused issues with users trying to use Outlook off-site and I'm not too sure how best to fix this problem.

I've run Microsoft's Connectivity Analyzer and found that the internal FQDN was being returned for a few different values. I'm going to post the returned XML below.

Needless to say, I'm trying to figure out how to make Autodiscover return the external mail FQDN so that everything works inside and outside of our network.

Any help you can give me would be appreciated. We're on Exchange 2010 SP3.

Thanks!

-Eric

Autodiscover XML (I redacted some of the server names just for safety, but indicated if it was returning the internal or external):

<?xml version="1.0"?><Autodiscover xmlns:xsd="http://www.w3.org/2001/XMLSchema" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://schemas.microsoft.com/exchange/autodiscover/responseschema/2006"><Response xmlns="http://schemas.microsoft.com/exchange/autodiscover/outlook/responseschema/2006a"><User><DisplayName>Eric Rovtar</DisplayName><LegacyDN>/o={MY DOMAIN}/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/cn=Recipients/cn={USERNAME}</LegacyDN><DeploymentId>2f14aef8-7381-4311-a2b0-5c7a5e16a7a4</DeploymentId></User><Account><AccountType>email</AccountType><Action>settings</Action><Protocol><Type>EXCH</Type><Server>INTERNAL-FQDN</Server><ServerDN>/o={MY DOMAIN}/ou=Exchange Administrative Group(FYDIBOHF23SPDLT)/cn=Configuration/cn=Servers/cn={SERVER NAME}</ServerDN><ServerVersion>7383807B</ServerVersion><MdbDN>/o={MY DOMAIN}/ou=Exchange Administrative Group (FYDIBOHF23SPDLT)/
					cn=Configuration/cn=Servers/cn={SERVER NAME}/cn=Microsoft Private MDB</MdbDN><ASUrl>https://INTERNAL-FQDN/EWS/Exchange.asmx</ASUrl><OOFUrl>https://INTERNAL-FQDN/EWS/Exchange.asmx</OOFUrl><OABUrl>https://EXTERNAL-FQDN/OAB/f023d8a7-80fa-4b45-ad31-3376703b7774/</OABUrl><UMUrl>https://INTERNAL-FQDN/EWS/UM2007Legacy.asmx</UMUrl><Port>0</Port><DirectoryPort>0</DirectoryPort><ReferralPort>0</ReferralPort><PublicFolderServer>INTERNAL-FQDN</PublicFolderServer><AD>INTERNAL-FQDN (DomainController)</AD><EwsUrl>https://INTERNAL-FQDN/EWS/Exchange.asmx</EwsUrl><EcpUrl>https://EXTERNAL-FQDN/ecp/</EcpUrl><EcpUrl-um>?p=customize/voicemail.aspx&amp;exsvurl=1</EcpUrl-um><EcpUrl-aggr>?p=personalsettings/EmailSubscriptions.slab&amp;exsvurl=1</EcpUrl-aggr><EcpUrl-mt>PersonalSettings/DeliveryReport.aspx?exsvurl=1&amp;IsOWA=&lt;IsOWA&gt;&amp;MsgID=&lt;MsgID&gt;&amp;Mbx=&lt;Mbx&gt;</EcpUrl-mt><EcpUrl-ret>?p=organize/retentionpolicytags.slab&amp;exsvurl=1</EcpUrl-ret>		<EcpUrl-sms>?p=sms/textmessaging.slab&amp;exsvurl=1</EcpUrl-sms></Protocol><Protocol><Type>WEB</Type><Port>0</Port><DirectoryPort>0</DirectoryPort><ReferralPort>0</ReferralPort><Internal><OWAUrl AuthenticationMethod="Basic, Ntlm, Fba, WindowsIntegrated">https://EXTERNAL-FQDN/owa/</OWAUrl><Protocol><Type>EXCH</Type><ASUrl>https://INTERNAL-FQDN/EWS/Exchange.asmx</ASUrl></Protocol></Internal><External><OWAUrl AuthenticationMethod="Fba">https://EXTERNAL-FQDN/owa/</OWAUrl></External></Protocol></Account></Response></Autodiscover>