How many cold emails per day per inbox is safe?
30 to 50 a day from a warmed mailbox, never more than 50. Why Google's 2,000 limit misleads, how to ramp, and how many inboxes you need.
Send 30 to 50 cold emails a day from one warmed-up mailbox, and no more than 50. A mailbox that is still warming up should send well under that, starting around 5 to 10 a day and climbing over a few weeks. If you need more volume, add mailboxes and domains. Do not push one inbox harder.
That is the short answer. The rest of this article explains where the number comes from, why Google's "2,000 a day" is the wrong figure to plan around, and how to do the math for the volume you actually need.
- cold emails a day per mailbox, the ceiling most practitioners use
- 50
- the median a mailbox actually sends per day in Smartlead's data
- 14
- rough ceiling for outbound mail per sending domain per day
- 500
The provider limits are not your limit
People search this question, find Google's sending limits, and conclude they can send 2,000 cold emails a day. Google Workspace does allow a standard account to send 2,000 messages a day, and a trial account 500 (Gmail sending limits in Google Workspace). Hit that, and the account can't send new mail for up to 24 hours.
But that limit is about abuse of the account, not about whether your mail lands in the inbox. A mailbox can stay far below 2,000 and still end up in spam, because inbox placement is decided by how recipients react: replies, opens, "this is spam" clicks, bounces. Cold email gets far fewer replies and far more complaints than mail between colleagues, so the safe ceiling is much lower than the technical one.
There is a second threshold to know about. Both Gmail and Outlook.com treat a sender of more than 5,000 messages a day to their consumer addresses as a bulk sender and demand stricter setup. Google requires SPF, DKIM and DMARC plus a spam rate under 0.3% in Postmaster Tools, and recommends staying under 0.10% (Email sender guidelines). Microsoft set the same 5,000 line for Outlook.com, Hotmail and Live addresses from May 5, 2025, and says it rejects mail from such domains that fails authentication (Outlook's requirements for high-volume senders).
Most small B2B teams never get near 5,000 a day. Set up SPF, DKIM and DMARC anyway. It costs an hour and removes a whole class of problems.
Why 30 to 50 per mailbox
No provider publishes a number for cold email. The 30 to 50 range comes from people who run outbound at scale and watch what happens to inbox placement as volume rises. Smartlead, which sends cold email for a living, puts it plainly: keep every mailbox at 50 cold emails a day or fewer, and run the full 50 only from a mailbox with a clean bounce history. In their own data the median mailbox sends 14 a day, and only the busiest 5% send 70 or more (Smartlead).
A safer working rule sits below the ceiling: 30 a day is the comfortable number, 50 is the line you approach only when reply rates are healthy and bounces are near zero. The reasons are practical.
- Replies come back to the same mailbox. At 50 new emails a day, with follow-ups, a mailbox handles well over 100 outgoing messages daily. Someone has to answer what comes back, in time.
- Follow-ups count. If you send three follow-ups, a mailbox that "sends 30 a day" to new people is sending far more than 30 messages once the sequence fills up. Count every send, not only first touches.
- Warm-up traffic counts too. If a warm-up tool is running on the same mailbox, its sends sit on top of your cold volume.
How to ramp a new mailbox
A fresh mailbox on a fresh domain has no history, and mailbox providers are suspicious of anything without history. The usual mistake is warming up for two weeks and then jumping straight to 50. Smartlead lists ramping a fresh mailbox from 0 to 50 in the first week as one of the common mistakes (same source).
A ramp for a new cold email mailbox
- Weeks 1–2: warm-up onlySPF, DKIM, DMARC set. Warm-up runs. No cold email yet.
- Week 3: 5–10 a dayYour best-fit prospects only. Watch bounces and replies daily.
- Week 4: 15–20 a dayRaise only if bounces stay under 2% and nobody marks you as spam.
- Week 5 on: 25–30 a dayHold here for a while. This is a normal working pace.
- Later: up to 50Only with a clean history and replies coming in. Back off at the first warning sign.
We covered the warm-up stage itself in how long to warm up a new email domain, and what bounce rate should make you stop in what bounce rate is acceptable for cold email.
Doing the math for your volume
Work backwards from the number of new people you want to reach each month.
Say you want 3,000 new prospects a month. That is about 140 a working day. At 30 per mailbox, you need 5 mailboxes. Put two or three mailboxes on each domain, so you need two domains. Each domain then sends roughly 60 to 90 cold emails a day, well under the 500 per domain ceiling.
| New prospects per month | Per working day | Mailboxes at 30/day | Domains (2–3 mailboxes each) |
|---|---|---|---|
| 600 | ~30 | 1 | 1 |
| 1,500 | ~70 | 3 | 1–2 |
| 3,000 | ~140 | 5 | 2 |
| 6,000 | ~275 | 10 | 4 |
Keep cold email off your main company domain. Use look-alike domains (for a company at acme.com, something like tryacme.com or acmehq.com) and point them to your site. If a cold domain gets burned, your invoices and support mail on the main domain keep landing.
Signs you are sending too much
You rarely get a clear "too much" error. You get slow drift. Watch for:
- Reply rate falling while the list stays the same. The same kind of prospects, the same copy, fewer replies. Often that means more of your mail is going to spam.
- Bounces rising above 2%. That is a list problem, but at higher volume it does damage faster.
- Spam rate in Google Postmaster Tools moving toward 0.1%. At 0.3% you are over Google's line. Our guide on a Gmail spam rate above 0.3% covers what to do.
- Replies saying "found this in spam". Take them seriously.
When you see any of these, cut volume by half on that mailbox for a week. Don't move the same list to a new mailbox; you will burn that one too.
Volume is rarely the real constraint
Teams that ask "how many emails can I send" usually want more replies, and volume is the slowest way there. Twenty emails that show you read the person's profile and their company site usually beat fifty generic ones. A better list and a letter written for one person do more than another mailbox.
The hard part is doing both at once: writing each email for one person and keeping every mailbox inside its safe pace, day after day. That is the work Nitrino takes on. It researches each person before the first letter, writes from your own mailboxes, and sets each account's daily limit by its health: bounces, DNS records and replies. When a signal gets worse, the limit drops at once and climbs back at most one step a week (how account safety works).
Whatever tool you use, the rule stays the same. Thirty a day from a warm mailbox, fifty at most, and more mailboxes when you need more reach.
