---
title: "Cold Email Warm-Up: The Real Per-Mailbox Daily Ramp"
url: https://trysumora.com/guides/cold-email-warmup-schedule
markdown-of: https://trysumora.com/guides/cold-email-warmup-schedule
---

# Cold Email Warm-Up: The Real Per-Mailbox Daily Ramp

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# Cold email warm-up schedule

A day-by-day cold email warm-up ramp, the complaint and bounce rates that should auto-pause a mailbox, and why per-mailbox volume caps far lower than most sequencers admit.

By Devansh Ranjan · Published Aug 7, 2026

**Short answer:** start at **20 sends/day** per mailbox, add **20/day**, plateau at **200/day** after 10 days. Auto-pause the mailbox at **0.3% complaints** or **2% bounces**. Scale by adding mailboxes, never by raising one mailbox’s cap.

Cold email fails differently from social outreach. LinkedIn restricts an account you can see; email quietly stops arriving, and by the time you notice, the domain reputation is already spent. The ramp below is what [Sumora](/) enforces per mailbox.

## The 10-day ramp

Day

1

2

3

4

5

6

7

8

9

10+

Sends/day

20

40

60

80

100

120

140

160

180

200

The plateau is the important number. 200 per day per mailbox is not a soft suggestion — it is roughly where single-mailbox reputation damage starts, and no sequencer changes that.

## The two numbers that should stop a mailbox instantly

Signal

Threshold

Why

Spam complaints

0.3%

3 per 1,000 sends. Providers filter well before this on a sustained basis.

Bounces

2%

The clearest signal of an unverified list. Compounds into domain damage fast.

These should be _enforced_, not reported. A dashboard that shows a rising bounce rate while continuing to send is a dashboard watching a fire.

## Suppression is not optional

Three categories must be permanently suppressed across every mailbox and every campaign, not just the one that triggered them:

-   **Unsubscribed** — legally required, and re-contacting is the fastest route to a complaint.
-   **Bounced** — a hard bounce re-sent is a deliberate reputation hit.
-   **Complained** — never contact again, on any domain.

Suppression scoped to a single campaign rather than the whole workspace is one of the most common and most damaging misconfigurations in cold email.

## Scale horizontally, exactly like social

Past 200/day you add mailboxes, each on its own ramp, ideally across several secondary domains. Same principle that governs [LinkedIn](/guides/linkedin-connection-request-limits) and [Instagram](/guides/instagram-dm-limits) — see [how horizontal scaling actually works](/guides/scaling-outbound-multiple-accounts).

And send from a **secondary domain** that redirects to your primary. Cold sending should never be able to damage the deliverability of the email your customers and investors use to reach you.

## Frequently asked questions

How many cold emails can I send per day from one mailbox?

Start at 20 per day on a new mailbox, add 20 per day, and plateau at 200 per day after about 10 days. Sending more than roughly 200 per day from a single mailbox is where reputation damage typically begins, regardless of the sending platform.

What bounce rate is too high for cold email?

A bounce rate at or above 2 percent should pause the mailbox immediately. Bounces are the clearest signal to a mailbox provider that you are sending to an unverified list, and they compound quickly into domain reputation damage.

What spam complaint rate is dangerous for cold email?

0.3 percent is a practical auto-pause threshold — 3 complaints per 1,000 sends. Providers begin filtering well before that on a sustained basis, so treat it as a hard stop rather than a target.

Should I use a separate domain for cold email?

Yes. Send cold outbound from a secondary domain that redirects to your primary, so reputation damage from cold sending can never affect the deliverability of your real company email.

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