I removed someone from my list and they still got my e-mail (that was sent later). I went back and checked the list and they were not on the list.
Where did I go wrong with removing them from my list?
Where was the email sent from?
If it was a nurture campaign, then removing someone from the list your used to add them to the program would not have removed them from the program itself. They would still be members of the stream until you run a flow action to pause them or change their program status to Not In Program.
If the email was sent through a smart campaign with wait steps, then the same thing applies. Once a lead is qualified for your smart list, removing them from the list, or any lists that were referenced, would not remove them from the flow of the campaign.
What do we mean by "removed from list" in this case?
Taylor Conway did you set them to Unsubscribed=True? Or did you remove them from a campaign in some other way?
If it's not a dupe (see Priyank answers) then John's cause is right. You can remove someone from a smart campaign with wait steps with a "remove from flow" flow step.
Hope this helps,
I think you had dupes for the same lead which you merged later, I think you need to check Lead' activity log. This might be one possibility.
I had a case where the lead was unsubscribed but they were also on a unknown distribution list e.g. firstname.lastname@example.org. Might be worth pulling a list by domain.