Email sequence
A sequence is a planned series of messages to the same contact over days or weeks, stopping as soon as they reply. Most replies to cold outreach arrive after the first message, not on it.
Three to four messages spread over two to three weeks is the range where added volume still adds replies. Past that, marginal replies collapse and complaints climb, which costs more in reputation than the replies are worth.
The strongest follow-ups add something rather than asking again. A second message saying "just bumping this" gives the reader no new reason to answer; one offering a different angle, a relevant example, or a smaller ask does.
The one non-negotiable is that a reply — any reply, including a refusal — stops the sequence immediately. Automation that keeps sending after someone has answered is the fastest way to convert a soft no into a spam complaint.