What’s the difference between delivery, acceptance, and inboxing?

These three terms represent different stages of email success:

Delivery means the message was not rejected or bounced. The sending attempt completed without immediate failure.

Acceptance means the receiving server explicitly took custody of the message with a positive SMTP response.

Inboxing means the message reached the primary inbox folder where users actually see and engage with mail.

You can achieve delivery and acceptance while completely failing at inboxing. Many senders celebrate high delivery rates while their messages languish unseen in spam folders.

Delivery gets you to port. Acceptance logs you at customs. Inboxing means your cargo actually reaches the intended warehouse.