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Listen bereinigen: Dublettenabgleich

Duplicate matching combines subscribers with the same content and different subscriber IDs under a single subscriber ID.

This way, you not only avoid multiple deliveries to the same recipient, but also collect all activities (clicks, opens) and interest values on a single subscriber.

No subscriber is lost due to duplicate matching. Their membership in subscriber lists also remains unchanged, i.e. the merged subscriber can easily belong to multiple subscriber lists.

What are duplicates?

Each subscriber has a unique subscriber ID. In practice, however, it happens that the same subscriber logs in multiple times or is imported multiple times.

Thus, subscribers with the same content receive different subscriber IDs and are therefore considered different recipients for ###system_name##. If these duplicates are not cleaned up, this leads to disadvantages completely unnecessarily.


Duplicates occur when you

  • ... create the same recipient more than once in the 'Abonnentenverwaltung', e.g. in different subscriber lists. Solution: Edit the existing subscriber assign him another list (tab 'List membership').
  • ... in the 'Anmeldesetup' allow multiple logins of the same subscriber. Solution: Choose a duplicate matching setup, because the duplicate will be cleaned immediately after the subscription.
  • ... have selected the 'add' or 'replace' import type for the subscriber-'Import'. Solution: Select the 'update and add' import type. This will update existing subscribers with the new import data and not create new duplicates with each import.

New duplicate matching

On the 'New search' tab, in the 'Match lists' area, select the subscriber list(s) in which duplicates are to be searched for. If you have selected more than one list, the search will be performed across all lists.

Then define the desired 'Match fields' and 'Follow-up action' or conveniently select a 'Dublettenabgleichsetup', in which you have already saved the desired settings.

Match fields

You determine which subscribers should be considered "content equal" by selecting the 'Match fields'. Typical examples:

  • Dispatch by email: same email address
  • Sending by SMS: same phone number
  • Sending by postcard: same first name + last name + street + house number + postal code + city + country

If several fields are selected, as in the postcard example, a duplicate is only recognized if all match fields match (AND-linked). Upper/lower case and spaces are ignored, i.e. "Hans" and "hans " are regarded as duplicates.

You decide how "strict" your duplicate search should be. An example: You advertise that signing up for your customer newsletter will be rewarded with a personal welcome voucher. Now Mr. and Mrs. Mustermann sign up separately, but both under the email address To ensure that both receive your personal voucher and are not duplicates, select email address and first name and last name as the matching field. Another popular option is to match the 'Email' and 'Customer Number' fields (if available).

Please note, however, that this stricter check generally leaves more duplicates, e.g. if the same recipient fills out the registration form with customer number today, but without tomorrow.

Follow - up action

The duplicates found can be automatically 'merged' or 'exported' via a follow-up action. If no follow-up action is selected, the search results page is then displayed and the desired action can be started manually:

'Export' creates a CSV file that you can save on your computer and edit manually.

'Merge' merges the found duplicates under the oldest subscriber ID in each case to preserve their valuable activity data (clicks, opens) and interest values in each case. The activity data and interest values of the newer subscriber IDs are discarded.

Whose subscriber fields should be taken over, you can decide yourself via 'Merge mode':

  • Subscriber with latest change: 

    The subscriber with the newest modification date is searched for within the duplicates and its field values are applied.
  • Subscriber with oldest change: As above, but with priority on the subscriber with the oldest change.

The option Accept only filled fields (recommended) should usually remain activated. This way you avoid the transfer of empty fields. For example, if you have selected 'Subscriber with latest change', the following will happen: If the field of the subscriber with the most recent change is empty, the subscriber with the second most recent change is looked up, and so on.  In this way, as many fields as possible of the merged subscriber are filled with as many new values as possible without emptying fields that are already filled.

After clicking 'Start' MAILINGWORK starts the duplicate matching and switches to the 'Search results' tab. Depending on the amount of subscribers and matching fields, it may take some time to complete the matching. Upon completion, you will be given the number of 'duplicates' and 'groups'. For example, if you match by email address and three subscribers with the email address are found, the result would be three duplicates of the group

The actions that can be performed at this point are: 'Results', 'Merge', 'Export' and 'Delete'. 'Delete' actually removes all(!) found subscribers, not only the duplicate part of the duplicates. With 'Export' you save a CSV file on your computer to edit the found duplicates e.g. via Excel. 'Merge' shows you the above-mentioned choice of merging mode and transfers the duplicates into one data set according to your choice. Via click on 'Results' you get a detailed view about the found duplicates.

Exception: If only two or three duplicates are found per group, you can decide manually for each individual subscriber field whether the values of subscriber 1 or 2 should be taken over.

A click on the trash can icon discards the search.

The 'Merge' and 'Export' tabs each show you the current status of your selected actions after the duplicate search.