What happens if my import contains duplicate email addresses?

An email can only exist once in a Campaign Monitor list. If the source you are using with the import wizard contains the same email on more than one row, they will not be duplicated in Campaign Monitor. A Campaign Monitor subscriber list stops duplicate emails being added during the import.

We will add the first line in the import we come to with that email, including all its mapped fields, and then skip the next encountered. We can't control the order of source rows on insert, either.

This means you may be sending the wrong contact's mapped field data over if you have duplicate emails in the report. This can be a problem for merging email content, but especially for segmentation using mapped field data.

Ensure your report includes only one instance of the email in all the rows to avoid this. You can also map Salesforce record IDs to override simple email matching, but your source report for setting those IDs must, again, only include the needed contact and not any of the dupes.

See more on overriding email matching

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