Having read their privacy policy and done a quick search for Dark River Systems (bottom of link's landing page, to the right) that would be a hard "Nooooop!" from me. Then again I guess that's why there are things like guerilla mail etc eh?
An interesting 5 minute rabbit hole tho and https://www.sapperlabs.com/code was a chuckle... for instance ---
"DISCLOSURE OF YOUR PERSONAL DATA Business Transactions
If the Company is involved in a merger, acquisition or asset sale, Your Personal Data may be transferred. We will provide notice before Your Personal Data is transferred and becomes subject to a different Privacy Policy."