We are running into an issue where a data extension used to send an email has a subscriber key e.g. 0003C00000Dkd3s from Salesforce but the actual send is going to another email address that has a subscriber key 0003C00000Dkd3S.

This is a major issue where the wrong person is getting our emails. Has anyone else dealt with this?


In the Marketing Cloud, the Subscriber Key field is not case sensitive. Using the 18 character ID instead of the 15 digit will eliminate the possibility of issues with duplicates.


In all SFDC products, 15 character IDs are case-sensitive. Salesforce also has 18-character IDs which are case-insensitive and they can be used interchangeably. There are many free tools to convert one to another.


The Subscriber Key in ExactTarget is not case sensitive. If you are sending to a Data Extension then I'm assuming you are not sending to a SF Contact (unless the SF/ExactTarget integration has been updated in recent months), but instead to a ExactTarget subscriber.

Are you sure the Data Extension is mapped on Subscriber Key to Subscriber Key? Are you also sure there is an Email Address data type field in the Data Extension (for in the case the subscriber doesn't exist in the All Subscribers yet?)

  • The list is coming from SF it's just that because we had to use an exclusion list with emails that are not in SF we exported from SF and imported to marketing cloud as a data extension.
    – Kyu
    Jun 17 '15 at 14:22

Use the LongSFID AMPScript function to get the correct 18 character id from the 15 character one. If you are using the MC Connector, it should already be 18 characters long

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