What is email deliverability?
Email deliverability is how likely your emails are to reach the inbox instead of the spam folder or being blocked. It depends on your sender reputation, authentication setup, list quality, and how recipients respond to your messages.
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Delivered versus inboxed
An email counts as delivered when the receiving server accepts it. That doesn't mean it reached the inbox, because it may still be placed in spam. Gmail's Promotions category is part of the inbox, although its visibility can differ from the Primary category.
Deliverability is about the second part: getting accepted and landing where people will see it.
What affects deliverability
Mailbox providers look at your sender reputation, whether your domain is properly authenticated, how often people mark you as spam, and how many addresses bounce. Engagement signals such as opens, clicks, and replies also play a part.
Sending to old or purchased lists tends to hurt, since those addresses are more likely to bounce or complain.
Basic ways to protect it
Authenticate your sending domain with SPF, DKIM, and DMARC, use a double opt-in or other clean sign-up method, and remove addresses that bounce or never engage. Gmail, Yahoo, and Microsoft now require authentication from bulk senders, and Gmail and Yahoo also require one-click unsubscribe and a low spam complaint rate. Make unsubscribing easy, because a quick opt-out is better than a spam complaint.
Common questions
What is email deliverability?
It's the likelihood that your emails reach recipients' inboxes. It goes beyond whether a message was accepted by the server and covers whether it avoided spam filtering.
Why do emails go to spam?
Common causes include poor sender reputation, missing authentication, high complaint or bounce rates, and content or links that look suspicious. Recipients who never engage can also push you toward spam over time.
What's the difference between deliverability and delivery rate?
Delivery rate is the share of sent emails the server accepted. Deliverability is the broader question of whether those emails reached the inbox.
How can you improve deliverability?
Authenticate your domain with SPF, DKIM, and DMARC, keep your list clean, send to people who asked to hear from you, and watch your bounce, complaint, and unsubscribe rates. Send consistently instead of in sudden large bursts.
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