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Translated from German; if the versions differ, the German version applies.
Metrics in newsletter marketing
After sending, every sending platform shows a series of percentages. The formulas behind them are simple – but not the same everywhere. Check in your platform what a rate refers to (emails sent or delivered, unique or all clicks).
The most important metrics
| Metric | usual calculation | tells you something about |
|---|---|---|
| Delivery rate | emails delivered ÷ emails sent | quality of the address list, technical set-up |
| Bounce rate | undeliverable emails ÷ emails sent | invalid addresses (hard bounce) or temporary problems (soft bounce) |
| Open rate | emails with at least one measured open ÷ emails delivered | subject line and sender – with major limitations (see below) |
| Click rate | emails with at least one click ÷ emails delivered | whether the content prompts action |
| Click-to-open rate | emails with a click ÷ emails with a measured open | how well the content convinces the readers who opened it |
| Unsubscribe rate | unsubscribes ÷ emails delivered | whether topic and frequency are right |
| Complaint rate | spam reports ÷ emails delivered | whether recipients feel harassed |
Example: 1,000 emails sent, 980 delivered, 49 recipients click at least once → click rate 49 ÷ 980 = 5.0%.
Why the open rate says little today
An “open” is measured by the email loading an invisible image from a server. With the Protect Mail Activity feature, Apple Mail loads remote content privately in the background as soon as an email arrives, and hides the IP address. The feature exists not only on the Mac but also on the iPhone; according to Apple, senders then cannot tell whether a message has been opened. To the sender this looks like an open – even if nobody has read the email. Our conclusion from this (not a measurement): open rates can appear considerably too high as a result.
Clicks, unsubscribes and – most important of all – what happens after the click (enquiries, purchases, sign-ups) are therefore more reliable.
Complaints: a figure that mailbox providers watch closely
In its Email sender guidelines for bulk senders, Gmail names a spam rate (measured in Postmaster Tools) that should be below 0.3%; elsewhere on the same help page it recommends staying below 0.1% permanently. Yahoo also names a limit of 0.3%. Anyone above this risks emails landing in the spam folder or being rejected.
Are there “good” values?
Comparative values (“benchmarks”) are mostly published by sending providers and depend heavily on the industry, the list and the measurement method. We therefore do not give any blanket values. It makes more sense to compare with your own previous mailings.