Email deliverability
Deliverability is whether an email you send arrives in the inbox rather than the spam folder or nowhere at all. It is decided by the receiving provider, not by you.
Also called Deliverability.
Deliverability is whether the email you send arrives in the inbox. It is distinct from delivery, which only means the receiving server accepted the message: an email can be delivered and still land in spam, where it counts as delivered by every sending tool and is read by nobody.
The decision belongs to the receiving provider, and it is made on evidence about the sender rather than on the content of the message. The inputs are the sending domain's history, whether the message is authenticated, how people who received your last emails behaved, and how closely this send resembles patterns the provider associates with bulk mail. Content matters far less than most senders assume, which is why rewriting a subject line rarely fixes a deliverability problem.
What is actually in your control is narrow but sufficient: authenticate properly with SPF, DKIM and DMARC; verify addresses before sending so bounces stay low; ramp a new domain slowly rather than starting at volume; make unsubscribing trivial so people use it instead of the spam button; and stop sending to anyone who has not engaged. All five are about the sender rather than the copy.
In practice
- A message accepted by Google and filed straight into spam: delivered, not deliverable.
- A new domain sending five hundred emails on its first day, with almost all of them filtered.
- A domain whose complaint rate crosses roughly 0.3%, after which Gmail begins filtering aggressively.
Questions
Why do my emails go to spam even though nobody reported them?
Because filtering is predictive rather than punitive. A receiving provider decides before anyone has read the message, using the sending domain's history, whether the mail is authenticated, and how similar the send looks to bulk patterns it has filtered before. A brand new domain with no history is treated as suspicious by default, and an unauthenticated message from one is treated as very suspicious. Absence of complaints is not evidence of good standing; it is usually the absence of a track record.
Does a spam-word checker help?
Very little. The idea that particular words trigger filters is largely folklore left over from filters of twenty years ago. Modern filtering weighs sender reputation, authentication and recipient behaviour far above wording. Time spent removing the word "free" is better spent verifying your list and fixing your DMARC record.
What is a good bounce rate?
Under 2%, and under 1% if you can manage it. Bounces are the fastest way to damage a sending domain because they demonstrate you are mailing addresses you have not checked, which is what a list bought rather than built looks like from the receiving side. Verifying addresses before sending is the fix, and it is cheap relative to the damage.
From the blog
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