There's a whole section called DELIVTERMS, focused on explaining email-related (and especially deliverability-related) terminology and acronyms.
I also try to report on issues around mailbox providers going offline (temporarily or permanently), and provide details of changes in sending requirements published by the different providers.
Email authentication is a big part of what I cover, as technologies like SPF, DKIM and DMARC are essential to successful email delivery in this modern age.
Spam Resource has received over 4 million views. Though, this counter starts when Blogger added tracking in mid-2010. The blog was already nine years old (and four years on the Blogger platform) by then. So it might be more like ... 4.1 million views.