With SAP Hybris Marketing on-premise it is possible to calculate the e-mail affinity score for each contact by using e.g. e-mail open and click behavior. With this approach you can determine if and how often a contact opens mails and clicks on links within the mails and use this in segmentation to filter out contacts which do not open their mails or only focus on customers which are highly engaged because they have a high click rate..
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Here you find a How-to-Guide for setting-up of affinity rules and you can freely extend or adapt this to e.g. to calculate the best sending time by defining a time interval.