Creating a high-quality mailing list is one of the most important tasks in email marketing. A high-quality contact base stands out through strong recipient loyalty and high activity. In order to display these, we need innovative performance figures, such as retention rate and segment engagement quotient.
Efficient email marketing requires – as every other marketing discipline – strategic planning. Targets must be set and operationalised in measurable sizes. Available are a number of KPIs (Key Performance Indicators). In addition to response data, there are also monetary quantities to determine the economic efficiency, as well as particularly innovative quality indicators, such as retention rate and segment quotient, which indicate the “value” of the mailing list over a longer period. These reflect the quality of the email contact data base, i.e. the loyalty of recipients and their activity.

Retention Rate

The retention rate indicates the strength of the recipient loyalty over a fixed period. It shows the percentage of how many recipients have remained or have been added to the list after this period expires. The number of recipients at the beginning of the chosen period is put into perspective with the number of recipients at the end of the period. It therefore expresses the list growth.
Retention rate = (Number of recipients)_t1 / (Number of recipients)_t0 * 100
t_1 = point in time after t_0
t_0 = point in time

Segment Engagement Quotient

The Segment Engagement Quotient (SEQ) is used to calculate the activity of recipients. The activity is shown on a scale from 1 to 10. Zero refers to complete inactivity, ten a hundred percent activity. The definition of activity or inactivity depends on the corresponding person in charge. Examples for sensible definitions of activity are netto conversions or netto clicks.
Segment Engagement Quotient =  (recipients total – inactive recipients) / (recipients total) * 10