Cold email capacity calculator
How many mailboxes and domains do you need to send your daily volume safely? Set your goal and a sensible per-mailbox volume, and see the numbers — using the same provider ceilings and warm-up ramp SalesScope enforces.
Most teams stay between 30 and 50.
You need
across about 5 sending domains, each sending at most 40 a day.
How the calculator works
It divides your daily goal by the volume you are comfortable sending from one mailbox, rounding up, and caps that volume at the mailbox’s provider ceiling less the 2% SalesScope keeps free for replies you send by hand. It then suggests a domain for roughly every three mailboxes, and counts the days a new mailbox needs to ramp up from 20 emails a day, growing 30% a day — SalesScope’s default warm-up.
Provider ceilings it uses
| Mailbox | Daily ceiling SalesScope enforces | Published provider limit |
|---|---|---|
| Gmail account | 500 | 500 recipients a day |
| Google Workspace | 1,500 by default (admin can set up to 2,000) | 2,000 messages a day |
| Microsoft 365 | Starts at 500 and warns past 2,000, the figure the calculator uses; never above Microsoft’s 10,000 | 10,000 recipients a day per mailbox, within a tenant-wide daily limit on external recipients |
| Outlook.com account | 300 | Not published for free accounts; 5,000 recipients a day with a Microsoft 365 subscription |
| Other provider over SMTP | 5,000 by default | Set by your provider |
The ceilings are hard limits. Cold email should sit far below them: what decides whether you land in the inbox is how recipients react, and a mailbox sending a few dozen relevant emails a day is a very different sender from one firing hundreds. Read the cold email deliverability guide before you scale.
Capacity questions
How many cold emails can one mailbox send a day?
Providers publish hard ceilings — 500 a day for a Gmail account, 2,000 for a paid Google Workspace account and 10,000 recipients for a Microsoft 365 mailbox — but those are limits, not targets. Cold email sent anywhere near them invites complaints and blocks. Most teams keep each mailbox to a few dozen cold emails a day and add mailboxes for volume. See Gmail sending limits.
Why does the calculator suggest several domains?
Each sending domain carries its own reputation. Spreading mailboxes across a few domains means one domain having a bad week does not stop all of your outreach. The calculator assumes about three mailboxes per domain; change that to suit your setup.
How long does a new mailbox take to reach full volume?
With SalesScope’s default warm-up ramp, a new mailbox starts at 20 emails a day and grows 30% a day, so it reaches 50 a day on day 5 and 200 a day by day 10. Your admin can change where the ramp starts and stops. See the warm-up guide.
Does SalesScope enforce these limits?
Yes. Every mailbox has one number for what it can still send today, inside its warm-up ramp and its provider’s ceiling, and SalesScope keeps 2% of the ceiling free for replies you send by hand. See how.
Related
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