You need a little education.
“Spam” is irrelevant or inappropriate messages sent indiscriminately to all audiences.
“Advertising” is the activity or profession of producing ads for commercial products or services.
What do I offer on my Web site? Information. Free-of-charge. No product nor service that benefits me personally.
SO … What I did - post ANTENNA PROJECTS to groups entitled “antennas,” “satellites,” and “DIY Projects” is really quite an appropriate use of the ‘Net. No spam. Target audiences.
Clint Bradford K6LCS
...Clint, do you really need to spam the internet with advertisements for your website?