Hello @DevAssociate ,
If you were trying to send a one-time email and just wanted to exclude contacts that were in a smaller list from your main list, then I'd suggest using segmentation and sending to that. However, based on how I'm understanding your description, this wouldn't work because you'd be constantly having contacts pop in and out of certain lists based on different prompts coming in. In this regard, you'd need to manually update your list(s) or make new ones to send to.
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