Email warmup is starting a new domain or mailbox at a low daily volume and raising it gradually, so mailbox providers see a steady sender whose mail is wanted rather than a sudden burst from a stranger. Google’s own advice is to start with a low volume sent to engaged recipients, increase it slowly, and avoid sudden spikes — even doubling from one day to the next. A practical ramp starts around 20 emails a day per mailbox and grows about 30% a day. For a brand-new domain, allow two to three weeks before full volume.
Key takeaways
- Sending reputation belongs mostly to your domain, and a new domain has none. Warm-up builds it from real, wanted mail.
- Start around 20 emails a day per mailbox and grow about 30% a day; for a brand-new domain, start at 10 and grow 15%. Never double overnight.
- Send your warmest mail first: customers, partners and recent inbound leads, then verified cold prospects.
- Warm-up tools automate engagement; a real sending ramp earns it. Neither fixes a bad list or bad copy.
- Watch placement, bounces and replies as volume rises, and hold the ramp at the first warning sign.
Why new domains and mailboxes need warming up
Mailbox providers decide where mail lands partly on the sender’s track record. Google’s email sender guidelines say Gmail tracks “volume, feedback, and limits per domain and IP address”, and that DKIM and SPF quotas are specific to your domain. A domain registered last week has no record at all, so filters have nothing to go on but what it does next.
If what it does next is send 300 emails on its first morning, it looks exactly like a spammer with a freshly registered domain. Google is explicit: “Avoid introducing sudden volume spikes if you do not have a history of sending large volumes. For example, immediately doubling previously sent volumes suddenly could result in rate limiting or reputation drops.”
Warm-up is the opposite pattern: a small, steady volume that grows a little each day, sent to people likely to read and reply. Each day of that is evidence in your favor. The same applies when you add a mailbox to an existing domain, move to a new sending provider, or come back after weeks of silence.
- Domain
- The reputation that matters most for cold email: the domain in your From address, your DKIM signature and your SPF record.
- Mailbox
- Each new sending address also starts without a history of its own volume and replies, so every new mailbox gets its own ramp, even on a warm domain.
- IP address
- Through Google Workspace or Microsoft 365, the sending IPs belong to the provider and are already in use, so there’s nothing for you to warm. You only warm an IP if you run your own mail servers or rent a dedicated one.
Before the first email
- Authenticate the domain. Publish SPF, turn on DKIM signing with your own domain, and add a DMARC record with
p=noneand a reporting address. Google recommends having SPF and DKIM working for 48 hours before you turn on DMARC. The SPF, DKIM and DMARC guide has the records. - Give the domain a home. Put a website on it, or redirect it to your main site, so anyone — prospect or filter — who checks the domain finds a real business.
- Set up real mailboxes. Real names, a profile photo, and a plain signature with your company and postal address. Avoid role addresses such as sales@ for cold sending.
- Check the domain’s past. If you bought a domain someone else used, look it up on blocklists such as Spamhaus before sending anything.
- Prepare a clean first list. Verify every address, and put your warmest contacts at the top — see email list verification.
- Make sure replies get answered. Early replies are the best signal you can earn; don’t let them sit.
A day-by-day warm-up schedule
The table shows two ramps. The standard ramp is SalesScope’s default: 20 emails on day 1, growing 30% a day until it levels off at 200. The gentle ramp is what we suggest for a brand-new domain with no history: 10 on day 1, growing 15% a day. The figures are daily caps covering everything the mailbox sends, first emails and follow-ups together. Sending fewer is always fine.
| Day | Standard ramp (20, +30% a day) | Gentle ramp for a new domain (10, +15% a day) |
|---|---|---|
| 1 | 20 | 10 |
| 2 | 26 | 12 |
| 3 | 34 | 14 |
| 4 | 44 | 16 |
| 5 | 58 | 18 |
| 6 | 75 | 21 |
| 7 | 97 | 24 |
| 8 | 126 | 27 |
| 9 | 164 | 31 |
| 10 | 200 | 36 |
| 12 | 200 | 47 |
| 14 | 200 | 62 |
The ramps are caps, not targets: each one grows until it meets the daily limit you set for the mailbox, so set that limit to the volume you actually plan. For cold email we suggest 30–50 emails a day per mailbox, follow-ups included. With a limit of 40, the standard ramp reaches it on day 4 and the gentle ramp on day 11. The gentle ramp keeps growing 15% a day if you need more, reaching 200 on day 23. SalesScope’s default warm-up ceiling of 200 is the most it will ever ramp a mailbox to, not a recommendation.
What to send as the ramp rises:
- Days 1–3: people who know you — customers, partners, people you’ve worked with at other companies — with short, personal messages that invite a reply. Mail between mailboxes on your own domain doesn’t count for much: it tells receivers elsewhere nothing.
- Days 4–7: recent inbound leads, conversations that went quiet, contacts from events and introductions.
- From day 8 (day 12 on the gentle ramp): verified, best-fit cold prospects in small batches, with plain-text first emails, at most one link and no tracking-heavy templates.
If you don’t have enough warm contacts to reach the cap, send fewer. Never invent traffic just to fill a number.
Warm-up tools versus a real sending ramp
There are two ways to fill the early days. Warm-up tools, sometimes called warm-up networks, enroll your mailbox in a pool of other users’ mailboxes. The service sends automated messages between members, opens them, replies, and moves any that land in spam back to the inbox, so your mailbox shows steady volume and engagement from day one. A gradual real-sending ramp uses only genuine mail to people you actually want to reach, starting small.
| Warm-up tool | Real sending ramp | |
|---|---|---|
| What builds the history | Automated messages and engagement inside a pool of mailboxes | Real messages to customers, contacts and prospects |
| Speed | Steady volume from day one, whatever your contact list | Limited by how many real contacts you have early on |
| Cost | A subscription, plus sending capacity: warm-up messages count toward your provider’s daily limit | No extra cost |
| The signals | Real activity in real mailboxes, but generated by software rather than interest | Every reply — and every complaint — is a real person’s reaction |
| Policy risk | Gmail’s program policies for personal accounts prohibit automating the Gmail interface “in a manner that misleads or deceives users”, and the Google Workspace Acceptable Use Policy prohibits testing or reverse-engineering the services “to evade filtering capabilities”. Whether a particular tool crosses those lines is Google’s call. | None beyond normal sending |
| What it can’t fix | A bad list, irrelevant targeting or complaint-prone copy | The same |
To be fair to both: mailbox providers haven’t published how they weigh warm-up pool traffic, so confident claims in either direction are hard to verify. What is certain is that a warmed mailbox — by any method — loses its standing quickly to a bad list or to copy people report as spam.
Do you need an email warmup tool?
Probably not, if:
- you have real contacts to send to in the first week — customers, partners, inbound leads;
- you can wait two to three weeks before a new domain reaches full volume;
- you plan a modest volume per mailbox, such as 30–50 cold emails a day, follow-ups included.
A tool may earn its place if you’re setting up many mailboxes at once with little real mail to send, or your mailboxes sit idle between campaigns. Either way, read your email provider’s terms first, and treat the tool as a supplement to authentication, verified lists and relevant copy, never a substitute.
Signs your warm-up is working
| Signal | Healthy | Warning — hold the ramp |
|---|---|---|
| Inbox placement tests | Inbox, day after day | Spam, or a tab such as Promotions, in more than the odd test |
| Bounces | Under 2% | Above 2%, or bounces saying a whole domain is unreachable |
| Replies | Arriving, including from cold prospects by the second week | None at all, or replies saying your email was in spam |
| Deferrals | None | 4.7.28 “unusual rate” or other temporary rejections |
| Postmaster Tools, if you send enough to personal Gmail | Spam rate under 0.1%; compliance status shows Compliant | Spam rate rising toward 0.3% |
When a warning appears, don’t push through it. Hold volume where it is, or step back a few days on the ramp, find the cause — usually the list, a link or an authentication gap — and resume only when tests are clean again.
Warm-up mistakes that undo the work
- Starting at full volume. Hundreds of emails on day one from a domain nobody has heard of.
- Doubling overnight. Google names this one explicitly; 30% a day is a sensible maximum.
- Warming up, then switching abruptly. Two weeks of light, friendly mail followed by 200 cold emails on Monday morning is still a spike. Move from warm to cold contacts gradually, inside the ramp.
- Bursts and silences. A whole day’s mail in five minutes, or Monday’s sending followed by nothing until Thursday. Google notes that you can increase volume faster “when you send daily instead of weekly”.
- Unverified lists. Bounces in the first week weigh heavily on a domain with nothing else to its name.
- Heavy first emails. Images, several links, attachments and tracking from a brand-new domain.
- Changing everything at once. Google advises that after “significant changes to your sending infrastructure or email header structure”, you increase that traffic separately. A new domain, a new tool and a new template on the same day leave you no way to tell which caused a problem.
- Too many mailboxes on one domain. Ten new mailboxes on a new domain multiply its first-week volume tenfold.
- Resuming at full speed after a break. After weeks of silence, ramp up again.
An established mailbox that already sends ordinary mail every day needs far less ceremony when you connect it to a new tool. What matters there is not changing its volume abruptly: raise cold volume on top of its normal traffic gradually.
How SalesScope handles this
SalesScope warms mailboxes with a volume ramp, not a warm-up network: it never sends automated warm-up messages or generates artificial engagement. Every mailbox has one number for what it can still send today, and while warm-up is on, the ramp is part of that number:
- The ramp starts at 20 emails a day by default and allows 30% more each day until it levels off at the warm-up ceiling, 200 a day by default — day 10 from the start.
- An admin sets where the ramp starts (5 to 300 a day) and where it levels off (50 to 2,000) for the workspace, and any mailbox’s own daily limit can be set lower — for example, to hold a brand-new domain back.
- The provider’s ceiling still applies: 500 a day for Gmail, 1,500 for Google Workspace by default and 300 for Outlook.com. A Microsoft 365 mailbox’s own limit starts at 500 a day, with a warning before it goes past 2,000.
- The mailbox screen shows which limit is setting today’s number, including the day of the ramp a mailbox is on.
- Inbox placement tests sent to spare Gmail or Outlook.com accounts you connect as test inboxes show whether the ramp is working, and the bounce circuit breaker puts a mailbox on hold if its bounce rate over the past 7 days passes the workspace limit (5% by default, once it has at least 50 sends).
Read more about deliverability guardrails, or work out how many mailboxes you need with the cold email capacity calculator.