Customers who’ve started using PosterMyWall can send only three email campaigns per day. As long as you have email sends, you can send emails for your three campaigns. After you’ve published 3 email campaigns, you can’t send a fourth email campaign on the same day.
As you interact more with the email publishing suite and reach out to larger lists, the limit will gradually be upgraded from three to ten emails per day.
A useful practice is to create a single campaign and use multiple mailing lists with the campaign instead of creating a new campaign for each mailing list.