Very good article with clear samples about usages of SPF, DKIM | 0x4516

Very good article with clear samples about usages of SPF, DKIM, DMARC records with their proc/cons in simple language.
SPF, DKIM, and DMARC are complementary systems. SPF and DKIM are used by email servers as indicators of whether or not an email is spam. DMARC then does two things: it tells email servers how important SPF and DKIM are, and what to do when an email fails to pass their tests.

This probably doesn't make much sense yet - that's fine. Let's dig a little deeper.

https://simonandrews.ca/articles/how-to-set-up-spf-dkim-dmarc