I am setting up a seed list for use in Marketing Cloud and the advice from the vendor is to try and randomly disperse the seed list emails throughout your sending DE, rather than tacking it on as an additional audience.

If I have a DE with 100k subscribers, where their SubscriberKey is their Salesforce ContactId, Email is Email, etc. At send time, Marketing Cloud would create batches for performing the send. Does it simply start at the top of the DE and work its way down based on the system's row ID? Does it alphabetise by the Primary Key in the DE?

How does Marketing Cloud choose which contacts to put into each batch at send time?

1 Answer 1


The order is first determined by the order in which the Data extensions are added to the send. THEN ordered by subscriberid ASC within each DE

So DE1 Subscribers 8 2 4 6

DE 2 subscribers 1 9 7 3 5

Would send in this order 2/4/6/8/1/3/5/7/9

  • Simple enough! Thanks. Is that documented anywhere? I'm interested to read more about it.
    – Ben
    Apr 20, 2021 at 0:30
  • I simply reviewed _sent dataview after a few sends
    – EazyE
    Apr 20, 2021 at 0:40
  • Ok thanks. Can I also confirm when you say SubscriberID, are you referring to SubscriberID (ie: the ID set in the background by MC that cannot be changed) and not SubscriberKey (ie the one we can choose to set ourselves)
    – Ben
    Apr 20, 2021 at 0:45
  • correct subscriberid not subscriberkey
    – EazyE
    Apr 20, 2021 at 0:48
  • Yeah ok so we have no control over the send order.
    – Ben
    Apr 20, 2021 at 1:16

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