How many cold emails can you send per day? (per mailbox, per domain, per campaign)

The question has two answers, and the gap between them is where most deliverability problems come from. The provider's technical limit for a Google Workspace mailbox is 2,000 messages a day. The number a cold-email mailbox can send day after day without ending up in spam is about 20 to 50. Everything below is about why, and what to do with that.

What the providers technically allow

These are the hard caps, from the providers' own documentation:

Hit these and the account is blocked from sending for up to 24 hours. But you will never get near them with cold email, because reputation gives out long before the cap does.

What reputation actually tolerates

Receiving providers score every sender on how recipients treat its mail: opens, replies, deletes-without-reading, spam reports, and how many addresses turned out not to exist. A mailbox sending cold email produces a poor version of every one of those signals — that is the nature of unsolicited mail — so the only lever you have is volume: few enough messages that the bad signals stay below the threshold at which Gmail or Microsoft decides the sender is bulk.

From running campaigns across hundreds of mailboxes, the pattern is consistent:

• New mailbox, first two weeks: 0 cold emails while warmup runs, then 5–10 a day.
• Established, warmed mailbox: 20–30 cold emails a day is the safe steady state. Reply rates hold and placement stays in the inbox.
• 30–50 a day: workable on an aged domain with excellent list quality and a long history, and only alongside continuing warmup. This is the ceiling, not the target.
• Above 50: placement degrades within days on most mailboxes. Some survive for a while; all of them eventually don't.

Microsoft-hosted mailboxes are stricter than Google-hosted ones in practice, so keep them at the lower end of each range.

Gmail's own guidance to bulk senders is to "start with a low sending volume to engaged users, and slowly increase the volume over time" (Google sender guidelines). The ranges above are that advice applied to a mailbox whose recipients are, by definition, not yet engaged.

Per domain, not just per mailbox

Reputation is also tracked on the sending domain. Ten mailboxes on one domain each sending 30 a day is 300 cold emails a day from one domain — and one bad list poisons all ten. Two or three mailboxes per domain is the usual limit, which means:

For 1,000 cold emails a day that is roughly 35–40 mailboxes across 12–15 domains, all warmed, all authenticated. That is a real cost — domains, mailboxes, warmup — and it is the honest reason cold email at scale is infrastructure work, not copywriting work.

Per campaign: the ramp

The third limit is how fast new people enter a campaign. Launching a 5,000-lead list on day one means 5,000 first emails in a day even if you have the mailboxes for it — and if 3% of those addresses are dead, that is 150 bounces in an afternoon, which is how domains get flagged.

Admit new leads gradually: 50–100 a day into a campaign, so a bad list shows itself at 100 bounces rather than 5,000, and follow-ups to earlier leads are spread across the same days as first emails to new ones.

Spacing inside the day

A mailbox that sends 30 emails at 9:00:00–9:00:30 looks automated no matter how good the copy. Space sends 15–30 minutes apart with random jitter, inside business hours in the recipient's timezone. Thirty emails at 20-minute intervals is ten hours of sending — which is why the daily ceiling and the gap fit together.

How MailFleet applies this

The defaults are the numbers above:

• A newly connected mailbox starts at 30 messages a day with a 20-minute gap, jittered ±30%; you can lower either per mailbox or in bulk.
• A campaign admits 100 new leads a day by default (adjustable), with a priority slider between new leads and follow-ups.
• Sending happens inside a window (09:00–16:30, Monday to Friday by default) in the campaign's timezone or each lead's own.
• Warmup runs alongside at 20 a day by default, never counted against the sending limit or your email credits.
• Mailbox rotation spreads a campaign across every healthy sender you attach, so adding mailboxes raises your ceiling without touching per-mailbox volume.
• A rising failure rate pauses the campaign and the Deliverability page flags a domain from 4% bounces so you can pause it before it's burned.

Worked example

You want to reach 2,000 prospects with a three-step sequence over a month.

• Total sends ≈ 2,000 × 3 = 6,000 over ~22 sending days ≈ 275 a day.
• At 25 a day per mailbox that is 11 mailboxes, which means 4–6 domains.
• Admit ~100 new leads a day; the campaign fills in 20 days and the follow-ups trail by the step delays.
• Warm the mailboxes for a week before launch, keep warmup on, and you are done in about five weeks including warmup.

Trying the same reach with two mailboxes at 140 a day each would work for about three days.

FAQ

How many cold emails per day from one Gmail account?

Google Workspace allows 2,000 a day technically. For cold email, 20–30 a day per mailbox is the sustainable range; 50 is the ceiling on an aged domain with a clean list.

How many cold emails per day from Outlook / Microsoft 365?

Exchange Online allows 10,000 recipients a day and 30 messages a minute. For cold email, treat Microsoft mailboxes as slightly stricter than Google and stay at 15–25 a day.

How many emails per domain per day?

Two or three mailboxes per domain, each at 20–30, so roughly 50–90 cold emails per domain per day.

How do I send 1,000 cold emails a day safely?

With about 35–40 warmed mailboxes across 12–15 domains, each sending 25–30 a day with 15–30-minute gaps, new leads ramped in at 100 a day, and warmup running throughout.

Does warmup count toward the daily limit?

Not in MailFleet — warmup sends are separate from the mailbox's sending limit and from your plan's email credits.