How many mailboxes do you need for cold email?

Based on 850 million+ emails · Smartlead platform data

The median account runs 20 mailboxes. The smallest 25% run 7 or fewer, the largest 25% run 60 or more, and the largest 5% run 535 or more. At the median pace of 14 cold emails a day, 20 mailboxes send about 280 a day.

Work out how many mailboxes you need

Cold emails you want to send per day

Mailboxes per account by percentile

Mailboxes connected to each account, with the daily volume they can carry. Built from more than 850 million emails sent through Smartlead.

Account	Mailboxes	Emails a day at 14 per mailbox	Emails a day at 50 per mailbox
Smallest 10%	3 or fewer	42	150
Smallest 25%	7 or fewer	98	350
Median	20	280	1,000
Largest 25%	60 or more	840	3,000
Largest 10%	214 or more	2,996	10,700
Largest 5%	535 or more	7,490	26,750

What the data shows

Most accounts run a few dozen mailboxes or fewer. Half run 20 or fewer, and three in four run 60 or fewer.

The top end is far bigger. The largest 10% run 214 or more, and the largest 5% run 535 or more, over 25 times the median.

Mailbox count sets the volume ceiling. At 50 cold emails a day per mailbox, the median account can send up to 1,000 a day. At the median pace of 14 a day, it sends about 280.

How this compares with common advice

Guides usually plan mailboxes from daily volume, often with 2 or 3 mailboxes per domain and 15 to 25 cold emails per mailbox a day. The median mailbox here sends about 14 a day, just under that range.

What this data can't tell you

It counts mailboxes per account, not per domain or per campaign. It doesn't show whether running more mailboxes changes reply rates.

How to use these benchmarks

Work back from volume. Divide your daily target by 50, the per-mailbox ceiling, for the minimum, and by 14 for the median pace.
Spread mailboxes across several domains, so no single domain carries every send.
Warm up every new mailbox before it sends. The average sender warms up for 8 days.
If you need new mailboxes, you can buy email accounts that come fully set up.
The unlimited mailboxes guide covers running large mailbox counts in one account.

Frequently asked questions

How many mailboxes do you need for cold email?

Divide your daily cold email target by 50, the per-mailbox ceiling, for the minimum. The median account runs 20 mailboxes, enough for up to 1,000 cold emails a day at that ceiling.

Is 20 mailboxes enough for cold email?

It matches the median account. At the 50-a-day ceiling, 20 mailboxes can send up to 1,000 cold emails a day, and about 280 a day at the median pace of 14 per mailbox.

How many mailboxes per domain for cold email?

This data counts mailboxes per account, not per domain. Guides commonly suggest 2 or 3 mailboxes per domain, so the median account of 20 mailboxes would span about 7 to 10 domains.

Methodology

More than 850 million emails sent through Smartlead, using combined, anonymous platform data only. Only senders with at least 500 emails sent in the period are included. Each account's count is the number of mailboxes connected to it. Daily volumes multiply that count by 14, the median emails per mailbox per day, and by 50, the per-mailbox ceiling.