It's not guaranteed
Sending an email doesn't guarantee it arrives. The receiving server decides: inbox, spam, or rejected — based on how trustworthy your mail looks.
Reputation is everything
Mail servers score your domain and sending IP on reputation. Send spammy-looking mail once and future messages suffer, even the legitimate ones.
Reputation is slow to build and fast to burn — one bad send can drag down every email that follows.
Authentication builds trust
Three checks — SPF, DKIM and DMARC — prove a message really came from you. Without them, filters treat you with suspicion.
Key takeaway
SPF, DKIM and DMARC are how you prove an email is really from you.