Email Deliverability
Whether your emails actually reach the inbox instead of the spam folder or nowhere at all.
Email deliverability is how many of your emails actually land in the inbox, rather than getting filtered into spam or blocked entirely. It is different from whether an email was 'sent' — you can send a thousand emails and have most of them never seen. Mailbox providers like Gmail decide this based on your sending reputation, how people engage with your emails, and your technical setup.
You protect it by verifying your sending domain, keeping your list clean of dead and unengaged addresses, and sending things people actually want to open. Mailing people who ignore you or mark you as spam drags down your reputation, which hurts delivery for everyone on your list — so a smaller, engaged list often outperforms a big, cold one.
Why it matters
Every email that lands in spam is marketing you paid to create but no one sees — deliverability decides whether your list is a real asset or a dead channel.