For example, if you try to go to:

https://192.168.0.1:1010

Your browser will get a redirect to something like:

https://www.yourdomain.com:1010/webmail/

If you're specifying an IP address, it's more than likely because the canonical name of www.yourdomain.com doesn't resolve to the IP address of your Webmail server, so this redirect won't work.

Instead, what you will need to do is add the webmail directory to your original URL request. Then you won't have to deal with the redirect. For example:

https://192.168.0.1:1010/webmail/