Everytime you make a change to a newsletter within a campaign, or create or change a rule, the campaign will be paused for safety.
Consider this, if you start editing a newsletter people are already receiving, then a half complete newsletter might be sent to some users. To remain on the safe side, we will automatically pause the newsletters to ensure no errors.
Sometimes when you add a new "rule" for auto subscription of members, the rule may include "too many new people". We run tests on new rules to detect how many people currently match the rule. We like to give you the chance to delete the rule before those people are added to the email queue. For this reason we will automatically pause the first step newsletter to ensure you are fully in control of who enters your mail queue.
It is a quick process to restart any newsletters which have paused. Just click "restart", confirm all the send parameters which should default to the last details entered, and press start.
Be assured that no one will receive the same newsletter twice.... However, please be careful when copying newsletters to new campaigns as there is no check between steps/campaigns for duplicate content.