However though, are the other 99.5% actually seeing your mails, or have most of them just blacklisted your domain and your mails now go to junk automatically?

I think the blacklisting/mark-as-spam is MUCH more prevalent than people unsubscribing due to the harvesting of active email addresses (as mentioned above).

This of course is hard to know. My open rates are in the 30% to 35% range for normal weekly stuff and shoot up to 60% for special events.

I don't think too many people have blacklisted me yet.

FWIW - I'm on your list and find your content's signal to noise ratio pretty high. I like how you continually push yourself to learn new things, and bring the reader along on your journey.