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I'm about to tune our autodiscover-config. For our main-domain it works perfectly. Now I'm about to add support for multiple domains.

In this article Jaap Wesselius describes how to add an additional virtual directory with an http-redirection to our main-domain-autodiscover-virtual-directory. He uses a 2nd IP-address for this but didn't mention why he is using a 2nd IP-address.

My question is: couldn't I just create a new virtual-directory in the default web site with the same IP for the redirect? What's the problem with it?

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up vote 0 down vote accepted

The reason has to do with the SSL certificate. It is unlikely that you want to purchase an SSL cert for all "autodiscover." SMTP domains you host. Using a second IP address gives you the ability to create a separate website that does not use SSL.

So your second autodiscover url would be:

The autodiscover.xml would then be set to redirect to:

This way you only need an SSL cert for

When searching for the autodiscover service a client will follow the following in this setup scenario for your Second SMTP domain:

  1. Tries (Fails)
  2. Tries (Fails)
  3. Tries (succeeds)

If the third option were to fail it would go on to look for SRV records (

You can not add a new virtual directory to the CAS default website to accomplish this. This is because you would then have two "autodiscover" virtual directories in the same site.

You could create a new site on the CAS and use the above outlined steps to accomplish this. However, this also would require you to set the default website to use a specific IP and add an additional IP to your CAS NIC for the new site. See the Autodiscover Whitepaper: Scenario 4

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I understood that I need this to forward to my ssl-autodiscover-site from my maindomain (because http-forwarding is not available with ssl). That's ok. But can't I just create a http virtual directory in my default web site which redirects to my maindomain-autodiscover? (I think I misunderstood IIS ;)) – wullxz Apr 20 '11 at 16:35
See Edits above – HostBits Apr 20 '11 at 16:53
Ok thanks. I think I got it now. I'm used to apache-virtual-directorys, which can look at the subdomain that has been used and 'route' the use to a specific real directory... But it is possible to let a normal (linux) web-server do the redirection-work (it holds the same maindomain)? – wullxz Apr 20 '11 at 17:00
I'd imagine you would be able to, although I have not done this. The client is going to be looking for the directory structure of /autodiscover/autodiscover.xml. So as long as it can find the autodiscover.xml file and the file properly redirects, it should work. – HostBits Apr 20 '11 at 17:03

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