Definition
Email deliverability describes how reliably your emails land in recipients' inboxes rather than in spam or not at all. An email can be "delivered" (accepted by the server) and still end up in spam.
What decides it
- Sender reputation — the history of your domain and sending IPs: bounces, complaints, engagement.
- Authentication — SPF, DKIM and DMARC prove you're allowed to send (explained).
- List quality — valid, relevant recipients.
- Engagement — replies and opens help; deletes without reading and spam reports hurt.
- Content — natural text, few links, no attachments in cold email.
- Volume patterns — sudden spikes look suspicious; steady, modest volume looks normal.
Delivery rate vs inbox placement
- Delivery rate — share of emails accepted (not bounced).
- Inbox placement — share that land in the inbox. Harder to measure; test with seed inboxes.
Improving deliverability
- separate sending domain for outreach
- full authentication
- warm up new inboxes
- clean, targeted lists
- relevant, personal emails that get replies
Related: deliverability basics · why emails go to spam
Example
Two senders email the same 500 prospects. One uses a new domain with no authentication and blasts 500 emails in an hour; many land in spam. The other uses an authenticated, warmed-up domain and sends 50 a day across several inboxes; most land in the inbox and get replies.
Key takeaways
- Delivered isn't the same as reaching the inbox.
- Reputation, authentication, list quality and content all count.
- Steady, modest volume beats sudden bursts.