Deliverability

Deliverability describes what happens to an email between the moment your platform sends it and the moment it appears in someone's inbox. Some messages are accepted by the receiving mail server, some bounce because the address is dead or full, and some are accepted but filed into spam or promotions. All three outcomes sit under deliverability.

It is not the same as your delivery rate, which only counts whether a server accepted the message, not where it put it. It is also not Sender Reputation, which is the scoring mailbox providers apply to your sending domain and IP. Reputation is one of the causes; deliverability is the result you observe.

The common calculation is delivered emails divided by emails sent. The honest denominator is everything your platform attempted, including hard and soft bounces. The flattering version quietly removes bounced and suppressed addresses first, which pushes the figure towards 100% and hides the exact problem you are measuring. Delivery rate still says nothing about spam folders, so inbox placement is tracked separately using seed addresses or engagement patterns by mailbox provider, such as Gmail opens falling while Outlook opens hold steady.

Sender Reputation is the score providers hold on your domain; deliverability is what that score does to your mail. SPF, DKIM and DMARC are the authentication records that prove you are who you claim to be. List Hygiene and a Sunset Flow remove dead addresses that cause bounces. Open Rate only measures mail that already arrived.