One-time email campaigns This is the most basic email marketing campaign. A one-time campaign to your lists that can be sent manually (window pop-up) or scheduled with cron. As with all campaigns, you may set triggers on one-time campaigns, apply filters and use a custom sender profile.
Recurring email campaigns Autoresponders, Drip email campaigns, Campaign series and Date-triggered campaigns are types of recurring campaigns.
Such campaigns run periodically at given intervals. You can create campaigns that repeat daily or every X days, weekly or every X weeks, monthly on an exact day of the month. E.g. every 21st, every last day etc.