· 6 min read · deliverability
The short answer: we send 30 cold emails per mailbox per day, follow-ups included, from mailboxes that have finished 14 days of warmup. Every campaign we run is built around that number.
The longer answer is that 30 is a planning choice, not a law. No inbox provider publishes a safe number for cold email, and anyone who quotes one as a measured fact is guessing. What we can explain is why we picked 30, what it depends on, and what should make you send fewer.
Why 30 a day
Three reasons, in order of importance.
It looks like a person. Inbox providers learn what normal sending looks like for a mailbox. An ordinary professional sends a few dozen emails on a working day. Thirty sits inside that range, so a cold mailbox at 30 a day does not stand out from the people around it.
It leaves headroom. Our warmup ramp ends at 40 emails a day. Running the campaign at 30 means no mailbox is ever at its ceiling. The gap absorbs replies you send by hand, the ordinary variation of a working week and the warmup conversations that keep running in the background.
It spreads the risk. At 30 a day, a campaign needs more mailboxes to reach its volume, and that is a feature. If one mailbox is flagged, it carries only a small share of the campaign, and the rest keep sending.
None of this comes from a published rule. It is the number we plan around because it keeps every mailbox ordinary and every campaign on schedule.
What counts toward the 30
The cap covers every cold email a mailbox sends in a day, not only first emails. Our sequence has four steps, so once a campaign is in full swing a mailbox's 30 is a mix of first emails and follow-ups.
Three things sit outside the cap:
- Warmup conversations, which continue throughout the campaign
- Replies you write by hand to interested prospects
- Your own everyday mail, which should never come from these mailboxes in the first place
Spread the 30 across the working day in the recipient's time zone, with random gaps between sends. Thirty emails in one burst at 9am is a different pattern from 30 spread over eight hours, and filters notice the difference.
How it scales
Because the per-mailbox number stays fixed, volume comes from adding mailboxes, and mailboxes come with domains.
The arithmetic for our Launch campaign:
- 30 emails per mailbox per day
- 12 mailboxes, three on each of four domains
- 360 emails a day across the campaign
- 28 days of sending, which covers 10,000 emails with a little room to spare
If you want more volume, add mailboxes and domains at the same ratio. If you want to send faster, the same applies. What does not scale is raising the per-mailbox number. A mailbox at 90 a day sends three times the email with far more than three times the risk, because it no longer looks like anyone real.
We work through the same problem from the other direction, starting from a total and finding the number of mailboxes, in how many mailboxes and domains you need for 10,000 emails. And we explain why we put three mailboxes on each domain in lookalike domains for cold email.
The ramp during warmup
A new mailbox does not start at 30. It starts at five, and it gets to 30 by sending real conversations that get opened and answered.
The ramp we run on every mailbox:
- Days 1 to 2: 5 emails a day, no history yet
- Days 3 to 6: 8 to 15 a day, opens and replies begin to accumulate
- Days 7 to 10: 18 to 27 a day, reputation forming
- Days 11 to 13: 30 to 36 a day, placement tested on Gmail and Outlook
- Day 14: 40 a day, ready for a campaign at 30
Cold sending starts on day 16. The extra day gives us time to read the placement tests and confirm every mailbox is ready. If tests show mail landing in spam, we do not launch.
During the first days of the campaign, the mix is all first emails, because no follow-ups are due yet. The total per mailbox still stays at 30. We cover why this ramp cannot be compressed in email warmup explained, and it is the whole of our email warmup service.
What should make you send fewer
Thirty is a ceiling for a healthy mailbox, not a target to hit no matter what. These are the signals that make us lower it.
Bounces. If a mailbox's bounce rate climbs, pause its sending and check the list before anything else. We plan around keeping bounces under 2 percent. A verified list is the cheapest way to stay there, which is why every lead from our lead sourcing passes two verification providers first.
Spam complaints. Google's ceiling for bulk senders is a 0.3 percent spam rate, and it recommends staying under 0.1 percent. Cold email reaches people who did not ask for it, so treat any rise in complaints as a reason to slow down and reread the copy.
Placement drops. If a seed test shows a mailbox landing in spam at Gmail or Outlook, rest it: stop its cold sends, keep it in warmup, and let the other mailboxes carry the volume for a few days.
Rate limits and lockouts. Google Workspace and Microsoft 365 both limit unusual sending. A mailbox that is asked to verify itself or is temporarily blocked is telling you something about its pattern.
Mailbox age and history. A mailbox that just finished warmup has less room than one that has sent cleanly for months. A domain that had problems before deserves a lower cap and a longer warmup.
Where your prospects' inboxes live. If most of your list sits on Microsoft 365, watch placement there closely. Microsoft began enforcing its own authentication requirements for high-volume senders to Outlook.com in 2025, and its filtering does not always behave like Google's.
What should not change it
Two things often tempt people to raise the number, and neither should.
A deadline. If a campaign has to finish sooner, add mailboxes. Pushing each mailbox harder trades a few saved days for a domain that may need weeks to recover.
A good first week. Early results on a healthy mailbox are not evidence that it can take double. Reputation builds slowly and drops quickly.
The short version
- Send 30 cold emails per mailbox per day, follow-ups included
- Spread them across the working day with random gaps
- Warm every mailbox for 14 days first, ramping from 5 to 40
- Scale volume with more mailboxes and domains, never more per mailbox
- Lower the cap when bounces, complaints or placement move the wrong way
Watching those signals every day is what launch and monitoring covers across the 28 days of sending. If you would rather not run twelve mailboxes yourself, start a Launch campaign sending 360 emails a day across 12 mailboxes.