Nothing in a sequence matters until the mail lands. This lesson is about the records inbox providers read before a single word of your copy is considered.
SPF is the list of servers allowed to send as you. DKIM is a signature on the message that survives forwarding. DMARC ties both to the address a person actually sees and tells receivers what to do when the check fails. They answer three different questions and none of them replaces another.
Since February 2024 Google and Yahoo require bulk senders to have all three. A domain with SPF and DKIM but no DMARC has nothing telling receivers what to do about failures, so the safe assumption on their side is that you are not who you say you are.
It measures the share of recipients who pressed the spam button, not the share who disliked the mail. Google publishes the line: never reach 0.3%, and work below 0.1%. That is roughly one complaint in a thousand sends, which sounds generous until you send to a list you bought.
A new sending domain has no history, so receivers treat it cautiously. The fix is boring: start with people who asked for the mail, send small volumes, and grow only while complaints stay flat. There is no product that skips this, whatever the sales page says.
Run the free domain check first, then tell us what it found. We come back with what we would fix first, at no cost.