You should've said that you want libre software instead. A custom license doesn't really make an open-source project just source-available, you're granted plenty of rights as an user to use that source. Source-available would be much more restrictive than this.
Bold claims and assumptions. If you want OSI open-source then say so.
In addition to the fairly generous interpretation of that case. You make the assumption people should even recognize OSI definition or the US courts. The OSI definition is very narrow, someone forbidding military use doesn't make open-source software just source-available. Say what you want, one group doesn't get to decide a term, especially not that black and white.
Significantly more precise from you would be to say OSI open-source or libre software if you want that. Open-source as a generic term is much more liberal.
> Restrictions. You agree not to: (i) sell, rent, lease, distribute,
sublicense, loan or otherwise transfer the Commercial Features to any third party;
(ii) alter or remove any trademarks, service mark, and logo included with the
Commercial Features, or (iii) use the Commercial Features to create a competing
product or service. Postalsys is not obligated to provide maintenance and support
services for the EmailEngine Software licensed under this Agreement.
This isn't a small change either, I don't plan on selling it, but calling it open source is a stretch.
Even MongoDB, which has arguably less strict restrictions, have given up on trying to label the SSPL as open source.
https://opensource.com/resources/what-open-source