The follow-up is the channel
Most founders treat the first email as the campaign and the follow-up as an optional nag. They have it exactly backwards. The first email is permission to send the second, and the second is where the pipeline actually lives. Sending once and giving up is the most common way to leave nearly half your results on the table.
Most of the pipeline is in the follow-up
Follow-ups generate 44% of all positive replies, and the first follow-up alone drives 26.41%. Read that again: more than a quarter of your interested replies come from the single email most people never send. The first touch is not the conversation, it is the knock on the door, and a knock that goes unanswered the first time is not a no, it is a not-yet. Treating the follow-up as the channel, rather than as a polite afterthought, roughly doubles what a campaign returns.
The cadence
The rhythm that works is tight and finite: 4-6 emails spread over 20-21 days, then stop. The argument for not dragging a sequence out past three weeks is simple, the returns are concentrated early and then they fall off. A short, disciplined sequence collects nearly everything a long one would, without the cost of pestering people who were never going to answer.
Every follow-up adds an angle
The single rule that separates a follow-up sequence that works from one that annoys is this: every touch adds a new angle, never "just bumping this up." "Bumping this" tells the reader you have nothing new to say and you are emailing for your benefit, not theirs. Instead, make email two a genuinely different reason to care, a relevant customer result, a specific outcome a similar company saw, a second angle on the trigger. Each touch should be able to stand on its own as a reason a busy person might reply, because for the people who skimmed past the first one, it is the only email they are really reading.
The break-up email
The last touch deserves special attention, because it quietly outperforms its reputation. The one-line break-up, the email that says you will stop reaching out and asks if you have the wrong person or the wrong time, pulls some of the strongest replies of the whole sequence. It works through a quiet bit of psychology: the implied withdrawal of attention, the easy out, the genuine respect of not chasing forever. People who ignored three pitches will answer a graceful goodbye. End the sequence with one, every time, because it converts the silence into either a real conversation or a clean close, and both are worth more than a prospect left dangling.