How is delivery rate calculated?
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Delivery rate is one of the simpler metrics to calculate. The formula: (Emails accepted by receiving server / Emails sent) x 100. So if you sent 10,000 emails and 200 bounced, your delivery rate is 98%.
In other words, delivery rate is the inverse of your bounce rate. If your bounce rate is 2%, your delivery rate is 98%. If your bounce rate is 0.5%, your delivery rate is 99.5%.
One thing to keep in mind: "accepted" doesn't mean "reached the inbox." Delivery rate measures whether the receiving server took the message. What that server does with it afterward, whether it routes to inbox, spam, or promotions, is invisible to your ESP. A high delivery rate combined with a low open rate can signal spam folder placement, not actual delivery to readers.
Your delivery rate is mainly controlled by list hygiene and suppression. Remove hard bounces promptly and suppress risky addresses before sending. Authentication (SPF, DKIM, DMARC) affects whether servers accept your mail at all, which also affects delivery rate. If your rate is falling, check your bounce categories to understand whether it's a list quality problem or a reputation problem. If you're not sure where to start, our free Email Header Analyzer can help you read delivery failure reasons directly.
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