Yes. The 'Image Hosting Plus' add-on is just to allow you more disk space to host your images on Benchmark Email servers. If you have your own website, you can provide the URL for the images in your email OR you can upload your images on any image hosting site and use that URL in you emails.

Without the 'Image Hosting Plus' add-on , you can still host around 10MB of images or 50 images (whichever is reached earlier)