The Smart Follow-up Schedule allows you to optimize the deliverability of your emails. This feature makes sure that you are not sending too many emails from the same mailbox on a given day (1st stage + follow-up stages).
The feature is activated by default when you schedule a new sequence. You can deactivate the Smart Follow-Up Schedule in the advanced settings in the sequence preview.
In case you try to schedule a sequence going out on days with high volume (i.e over 350 emails including 1st stages and follow-up stages), you will receive a warning in the sequence editor to adjust the schedule of the sequence.
You can simply accept the changes and your emails will be automatically scheduled to maximize deliverability.
Note: The Smart Follow-up Schedule will trigger a warning and suggest changes for any stage of the campaign, not only for the first stage.