Warming up a new domain in 30 days

When you spin up a new domain (or IP) for email marketing, mail providers — Gmail, Outlook, Yahoo — don't know you yet. You have no history with them, so they distrust you by default. If your first move is blasting 50,000 emails to a full list, that reads as a spam signal, and they'll punish you for it: you end up in the promotions tab, in spam, or blocked outright.

Warming up is the opposite: you start small, you show the provider you're a legitimate sender — low bounce rate, near-zero complaints, solid opens — and you ramp up volume as you earn their trust. This guide gives you the 30-day schedule that works, day by day.

1. Understand why you need to warm up

Sending reputation is built through consistency and good behavior over time. A new domain starts at zero: neither good nor bad, simply unknown. Every send is a chance to add positive signals (people who open, click, and don't complain) or negative ones (bounces, complaints, unsubscribes).

The key is pace. Spiking your volume overnight is the single most suspicious signal there is. Ramping it up in gradual steps is exactly what a legitimate, growing business looks like. Take a look at the curve shape you're aiming for:

Notice it's not a straight line up — it's a ramp that starts nearly flat and steepens over time. That shape is what tells the provider "this is real, not a spam blast."

2. Verify authentication first

Before you send a single email, make sure your domain is authenticated. Without SPF and DKIM properly published, no warmup schedule is going to save you — providers won't trust a sender who hasn't even proven ownership of their own domain.

If you haven't done this yet, stop here and take care of it with the verify your sender tutorial and SPF, DKIM, and DMARC step by step. It's half an hour of work that everything else depends on.

Good to know: arrobaMail's sending engine (aMailMTA) already ships with built-in IP warmup and adapts its speed to each provider. This guide is about warming up your domain and your sender reputation — the part of the job that's on you, because it depends on who you're sending to and how good your list is. No engine can do that part for you.

3. Week 1 — start with your most loyal contacts

The first week matters most. This is where you sort your list from your most engaged contacts (people who open everything, recent buyers) down to your coldest, and send only to the top.

• Volume: small. Start with around 50 sends on day one and work your way up (250, 500) by the end of the week.
• Who to send to: exclusively your hottest segments. You want people who are sure to open, because every open is a huge positive signal for a reputation that's just being born.
• What to avoid: old, generic addresses (info@, sales@) or any you're not 100% sure about. A bounce at this stage weighs a lot.

4. Week 2 — double gradually

If week one closed with low bounces and complaints and solid opens, you've earned some trust. Now you can double your volume every two or three days: from 1,000 to 2,000, to 4,000.

The golden rule this week: only scale up if the metrics agree. If bounces start creeping up or opens start dropping, don't push forward — hold at the same volume one more day until things settle.

5. Week 3 — widen your segments

With your reputation now taking shape, start folding in slightly colder contacts: the ones who open occasionally, the ones from several months back. Keep raising volume (8,000, 12,000), but now with a broader audience.

Tip: this is the moment it pays most to check the breakdown by device and by domain. If you notice one provider in particular (say, Outlook) is giving you a harder time, slow down for that segment specifically without stalling the rest.

6. Week 4 — reach your full volume

In the final week, you reach the volume you actually need (30,000, 50,000, or whatever your target is). By now, providers already know you: you have a track record of healthy sends, low complaints, and good engagement. That track record is your reputation — and it's what keeps you in the inbox from here on out.

7. What to measure every day

Throughout the whole process, watch these three metrics every single day — they're your control panel:

• Bounce rate: should stay low. If it climbs, you have a list-quality problem.
• Spam complaints: should be minimal (ideally under 0.1%). A single spike is an alarm.
• Opens: as long as they stay high, you're on track. If they drop, providers are starting to route you to promotions or spam.

You'll find all of this in each campaign's stats, summarized in your Health Score, which is worth checking daily at this stage.

8. What to do if things go sideways

Warming up isn't always a perfectly straight line. If at any point bounces spike, complaints rise, or opens tank, don't push through it:

1. Pause the big campaigns. Insisting when things are going wrong is exactly what finishes off a reputation.
2. Step back a level. Return to the previous day's volume, or even the previous week's, sending to your hottest segments.
3. Find the cause. Did you add a new list of dubious origin? A segment that's too cold? Fix that before ramping up again.
4. Give it time. Reputation recovers, but more slowly than it gets damaged. A couple of days of small, healthy sends usually gets the curve back on track.

Common mistakes to avoid

• Skipping warmup "because you're in a hurry." It's the fastest way to burn a new domain and drag months of problems behind you.
• Warming up with a purchased or stale list. Warmup amplifies whatever you feed it: if the base is bad, warming up just speeds up the disaster.
• Watching opens only. A high open rate alongside high bounces is still a problem. Watch all three metrics together.
• Raising volume on a bad day. If the metrics don't agree, wait. Patience is, literally, part of the technique.

Next steps

You now have the schedule for launching a domain without burning it. To go deeper:

1. Get the full picture of how your reputation is built and measured in deliverability and reputation.
2. Revisit authentication with SPF, DKIM, and DMARC step by step.
3. Learn to read the metrics you'll be watching every day in interpreting reports and metrics.