Definition
What is email deliverability?
Deliverability is the ability of an email to reach the recipient's primary inbox rather than the spam folder or an outright rejection. It depends on three things: the technical authentication of the sending domain (SPF, DKIM and DMARC), the reputation that domain has built up with mailbox providers, and the behaviour of recipients, meaning their opens, replies, complaints and unsubscribes.
The three components
- Domain authentication proves to mailbox providers that it really is you writing. SPF declares which servers are allowed to send on your behalf, DKIM adds a verifiable signature to every message, and DMARC states what to do when a message fails the first two.
- Domain reputation is the rating mailbox providers give your sending domain based on the history of your sends. It degrades quickly and takes weeks to rebuild.
- Recipient behaviour feeds that reputation: opens and replies push it up, spam complaints and bounces push it down.
The three act together. Complete authentication does not protect a domain whose recipients report its sends as spam.
The thresholds to respect and where to read it
Since the major mailbox providers tightened their requirements for volume senders, three elements have become non-negotiable: the three authentication settings, a complaint rate under 0.3%, and a one-click unsubscribe present in the message's technical header, not only in the footer.
Domain reputation and the spam rate can be read in Google Postmaster Tools, free of charge, for sends to Gmail addresses. Your sending platform, for its part, shows the bounces, complaints and unsubscribes of each send. Open rates have become unreliable since some providers preload images: the click remains the measure to follow.
What it says and what it does not
Deliverability is not the delivery rate your platform displays. A message accepted by the recipient's server counts as delivered, even if it lands in the spam folder. A 99% delivery rate can therefore hide collapsing deliverability.
It also says nothing about the quality of the message. A perfect subject line has no effect on an email no one sees, and you pay for the send anyway. That is why the cause of sends that stop producing with no explanation is almost always technical, not editorial.
Suppose a fictional company sends a monthly newsletter to 20,000 addresses. Its platform shows 99% of messages delivered, but clicks have fallen by half in three months. In Google Postmaster Tools, domain reputation has dropped from high to low and the spam rate is above 0.3%. The cause: 6,000 addresses imported after a trade show, without documented consent, whose owners do not remember signing up and report the send as spam. The delivery rate showed nothing. Deliverability, however, collapsed for the whole list, including the 14,000 subscribers who were expecting the send.
We treat deliverability as the first check on an email channel, before the subject line, the template or the frequency. A perfect message that lands in spam produces zero sales, and it cost the same to produce and to send. We check the three domain settings, the complaint rate and the share of the list with no open in six months before restarting a send.
We read a drop in deliverability as a list problem before seeing it as a tool problem. Removing dormant contacts often raises the absolute number of sales: the domain's reputation recovers, so the send reaches active recipients better. Paying for a smaller list that sells more is a trade-off that is hard to get accepted. We recommend it almost every time.
Not to be confused with
- Delivery rate
- The delivery rate counts messages accepted by the recipient's server, spam folder included. Deliverability measures those that reach the primary inbox.
- Open rate
- The open rate has become unreliable since some providers preload images. Falling deliverability shows up in clicks, complaints and domain reputation, not in opens.
- Onus of proving consent
- The onus of proving consent is a legal obligation of the sender. Deliverability is a technical measure, but a list without documented consent degrades both.
Related concepts
- Subscriber value
- Fatigue threshold
- Onus of proving consent
- Administrative monetary penalty
- Conversion rate
- Conversion
Further reading
- Email marketing: deliverability, segmentation and sequences
- Automated email sequences: driving sales without exhausting your list
- CASL and newsletters: consent, identification and unsubscribing
- Email list value: calculating what a subscriber is worth
- Quebec Law 25 and marketing: forms, cookies and email lists
Related services
Frequently asked questions
Why do my emails land in spam?
The most frequent causes are incomplete domain authentication, a complaint rate that is too high, or sending to contacts who do not remember signing up. SPF, DKIM and DMARC get configured before any other optimization, then the list is cleaned of contacts with no open in six months.
How do I know if my deliverability has dropped?
Look at clicks, not opens or the delivery rate. Clicks that fall while the platform still shows 99% of messages delivered are the classic sign. Google Postmaster Tools then confirms the diagnosis with the domain reputation and the spam rate on Gmail addresses.
Will cleaning my list cost me sales?
Often the opposite. Removing contacts inactive for more than six months improves the sending domain's reputation, which makes the following sends arrive better for active subscribers. The absolute number of sales often rises after a cleaning, even though the list is smaller.
