Deliverability
How many cold emails to send per day, per inbox and per domain
The short answer: 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. To reach 30,000 prospects a month with four touches you need roughly 40 inboxes across 14 to 20 domains, and that's the kind of infrastructure we build for clients.
The number per inbox
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.
The number per domain
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.
The math for your market
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) | Inboxes at 35 a day | Domains at 2 to 3 each |
|---|---|---|---|---|---|
| 1,000 | 3 | 3,000 | 136 | 4 | 2 |
| 3,000 | 3 | 9,000 | 409 | 12 | 4 to 6 |
| 10,000 | 4 | 40,000 | 1,818 | 52 | 18 to 26 |
| 30,000 | 3 to 4 | 90,000 to 120,000 | 4,100 to 5,450 | 117 to 156 | 40 to 78 |
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.
Ramp, don't switch on
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.
The signals that tell you to slow down
- Bounce rate above 2%. Stop and verify the list. Instantly's benchmark report sets 2% as the ceiling, and lower is better.
- Spam complaint rate approaching 0.1%. Gmail wants senders under 0.1% and never at 0.3%. Cut the segment that's complaining.
- Reply rate falling week over week on the same copy. Usually placement, not copy. Check Postmaster Tools.
- A blocklist listing. Pause the domain, request delisting, find the cause.
What about the 5,000-a-day rule?
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.
FAQ
How many cold emails can I send per day from one Gmail account?
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.
How many email accounts do I need for cold outreach?
Divide your monthly send volume by 22 working days, then by 35 emails per inbox. Reaching 3,000 new prospects a month with three touches needs about 12 inboxes across 4 to 6 domains.
Is it better to have more domains or more inboxes?
Both, in proportion. Two or three inboxes per domain keeps domain volume modest and limits the damage if one domain has a bad week.
Can I send cold email from my main domain if the volume is low?
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.
Sources
Keep reading
How to warm up an email domain: the 21-day schedule we use
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.
DeliverabilityCold email deliverability in 2026: what Gmail, Yahoo and Outlook require
What 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.
Cold email12 cold email templates that get replies in 2026
Twelve 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.
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