How long to warm up a new email domain for cold email

Plan on four to six weeks from buying a new domain to sending it at full cold volume. The first two weeks the domain mostly sits: DNS records in place, a real website, a few normal conversations. The next three to four weeks you ramp from a handful of cold emails a day to roughly 30–40 per mailbox, and you never go past that per mailbox. If you need more volume, you add mailboxes, not emails.

That is longer than the "two weeks and you're good" advice still floating around. It is also shorter than people fear. The real cost is not the wait. It is skipping it, burning the domain in week two, and starting again.

What "warming up" actually means

Nobody at Google flips a switch when your domain is 30 days old. Mailbox providers judge a sender by its history: how much it sends, how steady that volume is, how many people open, reply, delete unread or press "Report spam". A new domain has no history, so the first few hundred emails decide what the filters think of you.

Google says this outright in its sender guidelines: "Start with a low sending volume to engaged users, and slowly increase the volume over time," and avoid "sudden volume spikes if you do not have a history of sending large volumes" (Gmail sender guidelines). That is the whole theory of warm-up in two sentences. Everything else is a schedule.

The numbers that matter are the ones providers publish:

The sending limits come from Google's own Workspace limits page, and Yahoo's 0.3% ceiling from its sender best practices. Note what the 2,000 means: that is the point where Google stops you, not a target. A cold mailbox sending 2,000 a day will be in spam long before it hits the cap.

A week-by-week schedule

This is the schedule I would run on a brand-new domain for B2B outreach. The daily numbers are per mailbox and they are practitioner ranges, not provider rules. Providers don't publish a safe number, so start low and let replies and complaints tell you when to move.

Two details make most of the difference.

Use a separate domain. If your company is acme.com, send cold from something like acmehq.com or getacme.com and redirect its website to the main site. A spam complaint on a cold domain costs you that domain. A complaint on your main domain can push your invoices and support replies into spam too.

Verify every address before it goes into the ramp. In the first weeks a single list with 10% dead addresses does more damage than anything you write. Bounces are the clearest "this sender bought a list" signal a provider gets.

Warm-up tools: useful, but not the warm-up

Warm-up services connect your mailbox to a pool of other mailboxes that send each other messages, open them, reply and pull them out of spam. They are worth running in the background, especially in the first two weeks when you have nothing else to send.

They do not replace real engagement, and they can't fix a bad list. Google's own wording is "engaged users", and the most engaged users you have are people who already know you. In week two, write to ten customers and partners from the new mailbox about something real, a scheduling question or an intro. Their replies are worth more than a thousand automated round trips.

Signs you are going too fast

Watch these from the first cold email, not after a problem shows up:

• Replies stop while sends keep going. If last week's 5% reply rate is now zero on the same kind of list, assume you're landing in spam before assuming the copy got worse.
• Bounces appear. Any hard bounce in the first weeks means the list needs another verification pass. Pause the mailbox until it's clean.
• Spam complaints in Google Postmaster Tools. Add the domain on day one. At low volume the dashboards are often empty; once data appears, Google wants you under 0.1% and never at 0.3%.
• Placement tests land in "Promotions" or spam. Send to a few seed mailboxes of your own on Gmail and Outlook every week and look where the email lands.

When you see any of these, go back one step in the schedule for a week. Dropping volume early is cheap. Recovering a domain that's already in spam takes weeks, and sometimes it's faster to buy a new one and start over.

What to write while the domain is young

Early emails carry more weight, so make them the kind people reply to:

An example that works for a first touch:

Hi Maria, saw that Northwind opened a second warehouse in Rotterdam last month. When you added the first one, did inbound orders from new distributors go through sales or straight to ops? Asking because we help teams with exactly that handoff. Either way, congrats on the expansion.

No link, one question, and the question is easy to answer in a line. Replies like that are the strongest signal a young domain can earn.

After the warm-up: keep it boring

Reputation keeps moving after week six. A steady 30 a day beats 0 on Monday and 150 on Thursday. The unsubscribe rules count too: at 5,000 messages a day to Gmail you need one-click unsubscribe (Gmail sender guidelines), and Yahoo asks senders to honor unsubscribes within two days (Yahoo sender best practices). Most cold programs never reach that volume per domain, but a clear "reply 'no' and I won't write again" line costs nothing and saves complaints.

Follow-ups follow the same logic. Two or three, spaced by days, each with something new; we wrote about how many is enough in How many follow-ups before giving up.

The hard part is holding the pace for months: reading the signals daily, slowing down when accept or reply rates drop, stopping a mailbox when a provider pushes back. That's the part Nitrino takes over in campaigns. The agent writes each email right before it goes out, sets the pace by each account's health, and stops writing to new leads if a platform restricts the account. It only writes to leads with a verified work email.

Whether you use a tool or a spreadsheet, the rule is the same: start small with people who will answer, grow by steps, and treat 40 a day per mailbox as the ceiling.