autodiscover.xml || Invalid XML Request - Error: User does not exist.
Question asked by John C. Reid - 6/10/2021 at 10:51 AM
I really need to get autodiscover working. I have attempted this twice, and given up twice. Everything seems to be in place, but it just doesn't work. I think I am making progress though because I found something new I didn't see before.

First, what works. DNS is setup and everything seems to resolve ok. I have Certify the Web providing wildcard certs so anything coming in for a supported domain has a valid cert. The bindings are working in IIS as I can get to the login page using any of my host headers. The settings in SmarterMail are pretty default, at this point I am still only worried about IMAP, POP, and SMTP. I will license and add MAPI/EWS and EAS once I can get this working.

What I have found and I didn't find before is that when I went looking for the autodiscover.xml so I could see what it contained, I could not get to it. I started by going to https://autodiscover.mydomain.tld/autodiscover.xml because it is my understanding the webroot of the domain is where Outlook looks first. I got a 404 not found for that request. I then tried https://autodiscover.mydomain.tld/autodiscover/autodiscover.xml and this time I got a basic authentication dialog. Well, this is progress but it is also where I am stuck.

If I enter an invalid username and password combination the Basic Authentication dialog just resets and give me another try. Typically with basic auth you shoudl get 3-5 attempts and then a 401 error, but this seems to let me try indefinitely, which might be a security issue as it allows for automated brute force attempts at password guessing.

If I enter a valid username and password instead of getting the expected autodiscover.xml document, I get this:

Invalid XML Request - Error: User does not exist.

Server stack trace: 
   at MailService.Remoting.Mail.GetUserStatic(String email)
   at System.Runtime.Remoting.Messaging.StackBuilderSink._PrivateProcessMessage(IntPtr md, Object[] args, Object server, Object[]& outArgs)
   at System.Runtime.Remoting.Messaging.StackBuilderSink.SyncProcessMessage(IMessage msg)

Exception rethrown at [0]: 
   at System.Runtime.Remoting.Proxies.RealProxy.HandleReturnMessage(IMessage reqMsg, IMessage retMsg)
   at System.Runtime.Remoting.Proxies.RealProxy.PrivateInvoke(MessageData& msgData, Int32 type)
   at SmarterMail.RemoteInterface.IMail.GetUser(String sessionStr, String emailAddress)
   at SmarterMail.Logic.Remoting.RemoteMail.GetUser(String sessionStr, String email)
   at SmarterMail.Web.SyncProtocols.AutoDiscover.AutoDiscoverProcessor.DoWork(Object workItemState),
John C. Reid  / Technology Director
John@prime42.net  / (530) 691-0042
1300 West Street, Suite 206, Redding, CA 96001

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