Non-bounce rate is one of key indicators used for measuring email marketing performance, but is only named like that by few ESPs.
Non-bounce rate for an email campaign refers to the part of sent messages which have not generated a bounce sent back to the sender platform. If you send 10 000 messages and the ESP platform registers 500 bounces, then the non-bounce rate is 95%.
Delivery rate is more often used instead of non-bounce rate for the same calculation. It assumes that if there is not an email bounce message, it means that the message has been delivered. Nevertheless, delivery rate term may be seen as a little misleading because some messages can have been filtered out, blocked or delivered to a junk folder without generating a bounce message.
Thus, non-bounce rate seems to be a term giving a better vision of what is really calculated.
Non-bounce rate is an indicator of email files quality.
Non-Bounce rates according to Epsilon benchmark: