Deliverability

What it means

Deliverability covers what happens after a message leaves your server: whether the receiving server accepts it, and then where the mailbox provider files it. A message can be accepted and still land in the spam folder, so deliverability asks more than whether mail bounced.

Providers decide from signals they publish only in part: authentication (SPF, DKIM, DMARC), the reputation of your sending IPs and domains, complaints, engagement, list quality and content. Google's sender guidelines and Yahoo's sender requirements set the minimums for reaching their users, and both say mail that misses them may be rejected or sent to the spam folder.

Because most of these signals stay inside each provider, deliverability is measured indirectly: provider dashboards such as Postmaster Tools and SNDS, inbox placement tests, bounce logs and blocklist checks.