Email Deliverability
Email MarketingAlso: Deliverability Rate · Email Inbox Rate
Quick definition
Email deliverability is the measure of how many emails you send actually reach recipients' inboxes rather than bouncing or landing in spam. It is calculated as emails delivered divided by emails sent, expressed as a percentage. High deliverability depends on sender reputation, list quality and technical authentication.
Strong deliverability sits at the high end of the range. Anything showing a declining trend over consecutive campaigns is a signal to audit your list and check authentication records before scaling send volume.
How it varies across Australia
Deliverability rates across Australian senders vary sharply with list hygiene. Clean, permission-based lists with proper authentication sit well above average. Lists built through data purchases or that have never been cleaned sit meaningfully lower and often show declining trends over time.
See email performance benchmarks across Australian industries →The four things that decide deliverability
Mailbox providers score your sending domain and IP. High complaint rates and spam traps tank the score.
Three technical records that prove you are who you say you are. Missing any one flags you as suspicious.
Removing hard bounces, inactive subscribers and spam-trap addresses before they damage your reputation.
Mailbox providers watch opens, clicks and replies. Low engagement trains them to route you to spam.
What it actually means
Most email marketers think deliverability means 'did the email send?' It doesn't. It means 'did the email reach the inbox?' Those are different questions, and the gap between them is where a lot of marketing spend quietly disappears.
Mailbox providers like Gmail, Outlook and Apple Mail make their own decisions about where your email goes. They watch how recipients behave with your messages, check your technical authentication records, and score your sending domain over time. None of that is visible in your email platform's send dashboard.
The number your platform reports as 'delivered' usually means 'not hard bounced.' It doesn't mean 'reached the inbox.' Emails sitting in spam folders count as delivered. A campaign with a strong deliverability rate on paper can still be performing badly if the inbox placement is poor.
Good deliverability is built before you send, not fixed after. It comes from sending to people who want your emails, maintaining clean lists and having proper authentication in place. Sending at high volume to an unqualified list is the fastest way to destroy a domain's reputation, and reputation damage takes months to repair.
Deliverability isn't an email problem. It's a list-quality and reputation problem that shows up in your email metrics.
How to calculate it
Deliverability Rate = (Emails delivered ÷ Emails sent) × 100
Worked example. You send a campaign to 10,000 addresses. 9,820 are accepted by receiving mail servers. Deliverability Rate = (9,820 ÷ 10,000) × 100 = 98.2%. The remaining 180 are hard or soft bounces. Note: this rate says nothing about inbox placement for the 9,820 that were accepted.
The Australian context
Australian senders operate under the Spam Act 2003, enforced by ACMA (the Australian Communications and Media Authority). The Act requires express or inferred consent before sending commercial messages, a clear unsubscribe mechanism in every email, and honouring unsubscribe requests within five business days.
Non-compliance isn't just a legal risk. Spam complaints feed directly into mailbox-provider reputation scores. A sender who ignores unsubscribes will see complaint rates climb, which drives spam folder placement, which drives open-rate collapse. The legal obligation and the deliverability interest point in the same direction.
ACMA has levied fines against Australian businesses for Spam Act breaches. The deliverability argument and the compliance argument are the same argument.
Where people get this wrong
Related terms
Common questions
What is the difference between deliverability and inbox placement?
Deliverability measures whether emails reached the receiving mail server without bouncing. Inbox placement measures whether those accepted emails appeared in the inbox rather than spam. Your platform reports deliverability. Inbox placement requires a separate seed-list testing tool to measure accurately.
What are the most important technical records for email deliverability?
Three. Sender Policy Framework (SPF) lists the servers authorised to send from your domain. DomainKeys Identified Mail (DKIM) signs each email cryptographically. Domain-based Message Authentication Reporting and Conformance (DMARC) tells receiving servers what to do when SPF or DKIM fail. All three should be set up and verified before any bulk sending.
How do I know if my emails are going to spam?
Your open rate collapsing across a cold list is a signal but not proof. The reliable method is seed-list testing: sending a campaign to a set of real inboxes you control across major providers like Gmail and Outlook, then checking placement manually. Tools like GlockApps and Mail-Tester automate this.
How often should I clean my email list?
Hard bounces should be suppressed immediately after each send. Inactive subscribers, those who haven't opened or clicked in six to twelve months, should be run through a re-engagement campaign and then removed if they don't respond. Quarterly audits are a reasonable baseline for lists in active use.
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About New Rebellion
New Rebellion is a marketing intelligence consultancy. We build tools, score Australian businesses on how their marketing actually performs, and publish Debrief every day. This dictionary is part of how we work in the open.
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