A follow-up is a short email sent in the same thread when your first message got no reply. Editors get a lot of email, so a single, polite reminder recovers a meaningful share of conversations.
Good follow-ups add one new reason to care, like a new feature, a free account offer or a detail their readers would value. "Just checking in" gives them nothing to reply to.
Stop after one or two. Repeated nudges are the most common reason outreach emails get marked as spam, which hurts your sender reputation.
Example
Six days after pitching, Margin replies in the same thread: "One more thing that might matter: Margin now imports highlights from Zotero."
Putting it into practice
Where to use it: Follow-up email template and Outreach volume planner. For the longer version, read how follow-ups fit into a complete outreach process.