How do I resolve Bad Request - Invalid Hostname when accessing SmarterMail by http remotely?
Question asked by Pat O - 7/21/2017 at 1:52 PM
I've been a long time user of SmarterMail simply as a CalDAV calender server and love it.  Thanks for a great product.
Previously I used the built-in server, on SmarterMail v13 I believe.  
I have done a fresh install on a Win 10 Pro box of SmarterMail 16.0.6382, configuring IIS 10 with the wizard during SM installation.  I have one binding for the SM web site to Host name "localhost", Port 9998, all IPs.
On the SM machine I can access SM via browser with no problems at localhost:9998.
I remotely connect to the SM server machine via OpenVPN.  The SM server is my VPN host with an IP of
Under my old built-in SM server, I could access SM over the VPN at  Now when I try this, I get an HTTP Error 400 "Bad Request - Invalid Hostname" response.
I can access the default port 80 IIS page at
From the searches I have done this seems to point to an IIS configuration issue, but I have not yet determined how to resolve.  FYI Although this does not seem firewall related, I do have a port 9998 rule.
Any help is greatly appreciated!  Thanks

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Pat O Replied
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Got it.  Just needed to leave "Host name" blank on the binding in IIS manager instead of "localhost".

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