If a Data extension in Marketing Cloud is marked as Sendable Data Extension, does this mean all the records within this sendable data extension will be calculated as billable contacts?

1 Answer 1


No it doesnt. The billable contacts are contacts on the all contact list. By definition , a sendable data extension is a data extension that has a column mapped to the All Subscriber List. e.g if you have a ContactId that represents that SubscriberKey in that data extension, you would have to map it to SubscriberKey so that system can resolve it at send time.

Otherwise , the Data extension is just a data store.

Response to additional questions in comments:

  • Are all subscribers part of all contact? Yes they are. Susbcribers count as email studio audiences, while contacts are a more broad category (think omni channel, sms, push , etc)
  • You mentioned that subscriber key needs to be used in sendable data extension for system to start sending, what kind of send activities are supported?: Yes for emails, you can use any subscriberkey (a word of caution, best practice dictates that you use an externel system id (eg. SalesforceID) if its integrated with it. In addition to the if you dont use the 18 digit SFID as your subscriberKey then tracking from your sends will not be sent back. For SMS, the subscriberkey will be the mobile number yo of the subscriber.
  • What about customised send activities? Do you mean custom activities in Journey Builder? If yes these will be depend on which channel your are send off. It is import to think about the channels. What you use as subscriber/contact key will depend on the channel you are sending from.

This question might should shed further light on this topic : What is the difference between Primary Key Contact ID, Contact Key, Subscriber Key and Subscriber ID?


  • Hi Data_Kid, thank you for answering! it's very helpful! Btw, are all subscribers part of all contact? you mentioned that subscriber key neees to be used in sendable data extension for system to start sending, what kind of send activities are supported? email send? sms send? what aboud customized send activities? thx again!
    – StackBruce
    Jun 26, 2018 at 2:15
  • Will update my answer @StackBruce
    – 0xsegfault
    Jun 26, 2018 at 8:16
  • Hi Data_Kid, thank you! Yes correct, the custom activity here refers to the journey builder custom activities, for example, in our case, we have to define our own SMS/MMS sending activity (by connecting journey builder and 3rd party sms/mms service vendor) since Salesforce Marketing Cloud OOTB mobile studio doesnt work in China Market. we wondering what's the relationship between sendable DE and custom activity here
    – StackBruce
    Jun 28, 2018 at 10:11

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