What is email deliverability?
Email deliverability is whether your messages reach the inbox rather than the spam folder or nowhere at all. It depends mainly on domain authentication (SPF, DKIM and DMARC), sending reputation, and how recipients react to your mail.
Authentication is the entry requirement. SPF states which servers may send for your domain, DKIM cryptographically signs each message, and DMARC tells receiving servers what to do when those checks fail. Without them, mail sent on your behalf by any platform is far more likely to be filtered, whatever it says.
Reputation is the ongoing part, and it is earned by recipient behaviour. Replies and opens help; spam complaints and hard bounces to dead addresses hurt disproportionately. This is why sending to a purchased list damages a domain that was previously fine — the bounce and complaint rates alone are enough.
The structural point that surprises people: reputation attaches to the sending domain, so it is yours to lose. A tool that sends from its own shared domain protects you from that and also means the recipient is not really hearing from you. A tool that authenticates your domain puts your name on the envelope and your reputation at stake, which is the right trade only if the sending is disciplined.
See also
Twin-Sales is the selfnode twin that works on this. See what it does →