Yes, it should be possible to run your bot on IIS or in any other hosting service (including cloud hostings besides Azure) as explained here. You will have to make sure that your bot has an internet-accessible endpoint and a valid HTTPS cert.
Regarding the requirements for the HTTPS cert, I’m copying the info for this thread for your reference:
The Bot Framework requires that the x.509v3 certificate exposed by
your endpoint be current and valid. Most of the checks for “current
and valid” are standard checks for server certs: the CN must match the
hostname, it must not be expired, it must not be listed in a CRL, it
must have the correct set of EKUs, etc.Most importantly, your cert must chain to a root certificate authority
trusted by Microsoft. The latest list of these CAs is available here.
Also, you can register your bot and even enable the channels without deploying to Azure or any other hosting. You can temporarily use ngrok to create a secure tunnel to your localhost environment and test the bot in your email channel before exposing it to other users. BTW, you don’t need to Publish your bot in the BotFramework portal, just register it. Publishing is just for those bots that would like to appear in the Bot Directory.