Deliverability
Send 25 to 50 cold emails a day per inbox, run two or three inboxes per sending domain, and add domains rather than pushing any inbox past 50. Hunter's 2025 data found inboxes sending 20 to 49 emails a day replied 27% above average, while volumes over 100 a day hurt deliverability. Reaching 25,000 prospects a month with four touches is an infrastructure job, and that's the kind of infrastructure we build for clients.
An inbox is a reputation. Google Workspace allows 2,000 sends a day on paper, but that limit is for normal business email, not cold outreach to strangers. The number that matters is how much cold volume an inbox can carry before mailbox providers notice a pattern.
Hunter's analysis of 31 million outreach emails found that accounts sending 20 to 49 emails a day had a 5.7% reply rate, 27% above the average, that 50 to 99 a day performed similarly, and that going past 100 damaged deliverability. Our own programs run 25 to 50 cold emails per inbox per day, with warmup traffic on top, and hold a 99% delivery rate at that pace.
Rule of thumb: 25 to 50 cold emails per inbox per day. Warmup stays on at 15 to 25 a day alongside them.
Domain reputation is shared by every inbox on it. Two or three inboxes per domain keeps a single bad day from taking a large share of your sending with it, and keeps any one domain's daily volume around 100 to 150 cold emails. Buy inexpensive variants of your brand (a .co, a .live, a hyphenated .com), never your main domain, and point each at your website.
Start from the number of prospects you want to reach each month and the number of touches in your sequence.
| New prospects a month | Touches | Emails a month | Emails a day (22 days) |
|---|---|---|---|
| 1,000 | 3 | 3,000 | 136 |
| 3,000 | 3 | 9,000 | 409 |
| 10,000 | 4 | 40,000 | 1,818 |
| 25,000 | 3 to 4 | 75,000 to 100,000 | 3,400 to 4,550 |
Divide the daily figure by 35 emails per inbox, then by two or three inboxes per domain.
Replies and bounces remove people from the sequence, so real send counts run 15% to 25% under these figures. Even so, the table makes the point: reaching tens of thousands of prospects a month is an infrastructure job, not a copy job. It's why our sending infrastructure is built to carry more than 400,000 emails a day across many domains, and why no single inbox in it sends more than a few dozen. When you compare outside firms, ask each one how many inboxes and domains it runs per client. The B2B lead generation agencies we compared are a good starting list.
A new inbox goes through two to three weeks of warmup before its first cold email, then climbs from 10 a day to its ceiling over another two weeks. Adding 20 inboxes to a campaign therefore takes about a month to reach full volume. Plan for it.
Gmail applies stricter requirements to senders of more than 5,000 messages a day to Gmail accounts, including DMARC and one-click unsubscribe, and once a domain crosses that line it's classified as a bulk sender permanently. With cold email spread across many domains at 100 to 150 a day each, no single domain gets near it. Meet the stricter rules anyway. They're the right setup regardless of volume.
Keep cold email to 25 to 50 a day per inbox, plus warmup traffic. Google's technical limit is far higher, but cold volume past about 50 a day from one inbox starts to hurt placement, and past 100 it measurably hurts reply rates.
Divide your monthly send volume by 22 working days, then by 35 emails per inbox, and put two or three inboxes on each domain.
Both, in proportion. Two or three inboxes per domain keeps domain volume modest and limits the damage if one domain has a bad week.
You can, and it's still a bad idea. Reputation damage to your main domain affects every email your company sends. Use separate domains even for a small program.
A step-by-step email warmup guide: what to set up before day one, a 21-day sending schedule per inbox, what to watch, and when a domain is ready for real cold email volume.
Read the warmup scheduleWhat Gmail, Yahoo and Outlook require from senders in 2026: SPF, DKIM and DMARC, spam complaint rates, one-click unsubscribe, enforcement dates, and how to set up cold email so it reaches the inbox.
Read the requirementsTwelve cold email templates we use in client campaigns, with the reasoning behind each one: the trigger email, the question email, the referral ask, the breakup and more. Under 80 words, one ask, no fluff.
Read the templatesThirty minutes with the founder. You'll leave with a clear picture of your market, what a campaign would look like and what it would cost.
Or email sales@beleaded.com