ANON_BM, you have perfectly described our situation with your truck site analogy.
We run a site about model trains. Here is a small portion of the menu structure from that site:
Train Forums
Traditional 3-Rail O Gauge
2-Rail Scale Forum
3-Rail Scale Forum
Tinplate Trains
O Scale Narrow Gauge Forum
S-Scale Trains
Subways/Transit/Traction
Real Trains
Layout Building Forums
Track Plans and Layout Design
Electrical Forum
Scenery and Structures
etc.
- Someone who is into Traditional 3-Rail O Gauge trains has NO interest in the 2-Rail Scale stuff.
- Same for someone into Tinplate Trains. He has NO interest in the Narrow Gauge, Subways or Real Trains, etc.
- The Narrow Gauge guy has NO interest in Subways.
- You get the idea...
We cannot just lump everyone into a single, site-wide basket when it comes to email digests and notifications.