# Deliverability Score Calculator

## Method

#### Goal

The calculated deliverability score is intended to provide a accurate assessment of the proportion of e-mails deleted or corrupted by spam filters.

The Deliverability Score affords users several advantages that other delivery metrics in the combination do not offer:

• Direct Metrics (Compared to Indirect Deliverability Metrics like IP Reputation or Complaints)
• Simple Calculation
• Easy interpretability (loss of response or number of missing opens can easily be translated into sales losses)
• Applicable to individual e-mail campaigns and groups of e-mails (e.g., all in month N)
• Validity shortly after the start of the dispatch

#### Approach: DROPS

The basic idea of the calculation approach is that delivery problems always show up in a drop in the responses, and that this drop in the response rate is different from domain to domain because the spam filters of the individual recipient domains do not match each other (except for company groups like 1 & 1, which use same or similar spam filters for different domains).

If the drop of the response rate is similar for all major domains, then the probability of delivery problems is much lower than in the case of high fluctuations in the response rates.

For example, if the rate opening rate of t-online, web.de, gmail and hotmail campaigns are between 20-25% below the average, then factors such as subject, sender or time of mail may explain the drop more plausible than spamfilter problems. However, if the drop would be 80% for gmail, and the other domains remain at between 20-25%, then there is a high probability of a spam filter problem.

Therefore, the algorithm for calculating the deliverability score first selects the domain with the lowest intrusion in the response. With this domain, the probability of spam filter problems is obviously the lowest. This is the reference delivery rate that any other domain should be able to reach with good delivery. Then, for each other domain, the amount of the missing openings is calculated from the difference to the reference delivery rate and the share of the distribution list. The deliverability score is then calculated as an aggregated relative index number over all domains, and describes the proportion of the measured openings compared to the expected openings at optimal delivery.

This Method can be characterized with the Acronym DROPS (Domain Relative Open Rate Score) .