What is email deliverability?
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Email deliverability is whether your emails actually land in the inbox. Not just whether they were sent, not whether the server accepted them. But whether the person you're trying to reach actually sees them.
The distinction matters because sending and delivering are different things. An email can leave your server, clear your ESP's queue, and still end up in spam, in the Promotions tab, or simply disappear. Deliverability is the full journey: from your sending infrastructure through mailbox provider filtering to inbox placement.
Four things mailbox providers check when deciding where your email goes:
Authentication: did this actually come from who it claims? That's SPF, DKIM, and DMARC. Reputation: does this sender have a history of sending wanted email? Filtering: does the content or structure look spammy? Engagement: do recipients interact with email from this sender, or ignore and delete it?
If any of those are off, you won't necessarily get a bounce. You'll get quietly routed to spam.
Deliverability problems are often invisible until they're serious. If your open rates have been declining and you haven't changed your content, or a campaign that usually performs well suddenly didn't, inbox placement is worth investigating. The free Blocklist Checker is a quick starting point.
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