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?