autodiscover.xml settings

captain-crash-xx1

I'm testing grommunio in a small AD environment. I've setup the server using the internal FQDN (mail.domain.local) and I've created three domains - one for the internal domain (domain.local) and two for domains I have (domain.com & domain2.com). I've created the internal & external DNS records - mail.domain.local and autodiscover.domain.local point to the servers IPv4 and IPv6 addresses, mail.domain.com and autodiscover.domain.com point to the external NAT'd IPv4 address of the server and the IPv6 address points to the real IPv6 address. I created a CSR with all the potential hostnames as SANs and I've signed this with the internal CA and this works as expected. I've configured LDAP to speak to AD and I've successfully imported some users.
I'm struggling to understand what needs doing with regards to the autodiscover.xml. If I use the Outlook 'Test Email AutoConfiguration', all the URLs show the external hostnames. The Exchange MAPI has entries for MAPI HTTP Mailstore Internal & External URLs and MAPI HTTP Addressbook Internal & External URLs. The hostname for all of them is the external hostname. Luckily this works for internal clients as it resolves to the real IPv6 address and this is used. An internal IPv4 only client won't work though as it can't reach the external NAT IPv4 address due to the hostname. An external IPv4 client should work though.
I'm fairly sure with Exchange 2016 I could set the Internal & External hostnames differently.
I've read through this https://community.grommunio.com/d/753-why-the-hostname-is-so-important-for-grommunio and configured what it says with the Server localhost etc, but still see the same behaviour. I think I might be missing a concept or something.

crpb

I'm a bit lost in that block of text but anyhow..

For internal Outlook stuff you probably just want to configure the Registry-Settings via GPO: https://community.grommunio.com/d/444-scripting-snippets-notepad/26

There is no Internal/External Hostname like in Exchange as that is a somewhat deeper thing in the active directory IIRC...

Either you NAT/Forward on your firewall anything from your local net that wants to access the external host/ip to your actual grommunio host or send it to your inbound proxy or something.
"Split-DNS" usually works aswell if your internal and external domains differ. Of course more maintainenance on that that copy of an external domain but well... it's not like you will have changes every day/week/month 🙈

WalterH

One simple solution is to set up split DNS so that the internal DNS server resolves external DNS names to internal IP addresses.

Further information can be found at: https://learn.microsoft.com/de-de/windows-server/networking/dns/deploy/split-brain-dns-deployment .