Hello @LingX8 ,   So checking your automation, you set a very very specific delivery window (week day and time range) for the overall series. What this means is that if you didn't get those contacts added to your list soon enough based on that initial 10hr queue, and they fell outside of the date and time range you set for the automation's overall deliveries, then they won't be able to send for essentially another week.   I'd advise editing your automation's delivery window to something much more open and available. Otherwise you'll continue to run into these kinds of issues. ... View more