When enrolling many contacts in workflows at once, you may experience what's called throttling. You can learn more about throttling here. The key takeaway is that workflows can process enrollments for up to 20 contacts per second, so if you're enrolling a lot contacts at once, some contacts may not be enrolled right away.
When using a fixed-date workflow, this delayed enrollment can cause contacts to miss the first workflow action if that first action is scheduled for a time that is soon after you bulk enroll the contacts. Let's look at an example:
- You have a fixed-date workflow in which the first action is scheduled for 3:30pm
- You activate the workflow and choose to enroll contacts who currently meet the workflow starting criteria at 3:00pm. There are 54,000 contacts who meet the starting criteria when you activate the workflow.
- HubSpot begins processing the workflow enrollments for those 54,000 contacts, enrolling 20 contacts per second. Math break! 54,000 contacts / 20 contacts per second / 60 seconds per minute = 45 minutes for all contacts to be enrolled
- As a result of this workflow enrollment throttling, some contacts will not enter the workflow until after 3:30pm when the first action is scheduled and will miss the first action.
What can you do about this?
Take the number of contacts that will be enrolled in the workflow and divide it by 1200 to determine how long it will take to enroll all of those contacts. If necessary, update the scheduled time for your first action to ensure you allow enough time for all contacts to get enrolled (using the example above where 54,000 contacts are enrolled at 3:00pm, you should schedule the first action at 3:50pm or later because it will take 45 minutes to enroll all of those contacts).
Pro tip: if you're choosing to enroll the contacts who already meet the criteria and the estimated number of contacts hasn't yet been processed, try refresh the page because the number of contacts who meet the starting conditions has likely been processed by the time you get to this point in the article. Once refreshed, click the toggle switch to turn the workflow on. This will open the activation modal where you should see the number of the contacts who meet the starting criteria.