How to Warm Up a New Email Domain (Without Landing in Spam)
A practical warm-up plan for a new sending domain: authenticate first, start with engaged subscribers and increase volume gradually.
In short: Set up SPF, DKIM and DMARC before you send anything, start with small sends to your most engaged subscribers, roughly double your volume every few sends while bounces and complaints stay low, and slow down at the first sign of trouble. Most small lists can be fully warmed up in two to four weeks.
Mailbox providers like Gmail and Outlook don't trust what they don't know. A brand-new domain — or an existing domain that's never sent marketing email — has no reputation yet. If its first send is thousands of emails at once, filters treat that like a spammer's burst. Warming up means building that reputation gradually, with emails people want.
When you need to warm up
- You've registered a new domain for your business or for sending.
- You're switching email platforms and sending from new infrastructure.
- You're sending marketing email for the first time from a domain that only sent day-to-day mail.
- You've not sent for several months and your list is large.
- You're sending from a dedicated IP address (rare for small businesses).
If you're sending a few hundred emails a month to people who know you, you don't need a formal plan — but the principles below still help.
Step 1: Authenticate before the first send
Add these DNS records for your domain before warm-up starts:
- SPF — which servers may send for your domain.
- DKIM — a digital signature on every email.
- DMARC — a policy that ties them together; start with p=none.
Gmail and Yahoo require authentication for bulk senders. Without it, no amount of warming up will help. Step-by-step setup is in SPF, DKIM and DMARC explained.
Step 2: Start with your best subscribers
Your first sends should go to the people most likely to open, click and not complain:
- Customers who bought recently.
- Subscribers who joined in the last 30–90 days.
- People who clicked an email recently.
Positive engagement in the first weeks is what builds a good reputation. Save older, less engaged parts of your list for later in the warm-up.
Step 3: Increase volume gradually
A simple schedule for a list of around 10,000 contacts:
| Send | Recipients |
|---|
| 1 | 250 most engaged |
| 2 | 500 |
| 3 | 1,000 |
| 4 | 2,000 |
| 5 | 4,000 |
| 6 | Rest of the engaged list |
| 7+ | Gradually add older contacts |
Space sends at least a day or two apart. As a rule of thumb, never more than double the volume from one send to the next. Smaller lists can move faster; larger ones should take longer.
Step 4: Watch the signals after every send
- Bounce rate — keep it under about 2%. Higher means old or bad addresses; clean before continuing.
- Spam complaints — keep them under 0.1%. Gmail's bulk sender rules require staying well below 0.3%.
- Opens and clicks — should look normal for your list. A sudden drop suggests spam placement.
- Test inboxes — keep seed addresses at Gmail, Outlook and Yahoo on your list and check where your emails land.
- Google Postmaster Tools — free; shows your domain's reputation and spam rate at Gmail once you send enough volume.
Step 5: Slow down when something goes wrong
If bounces or complaints rise, or emails start landing in spam:
- Pause increases — repeat the last volume that worked.
- Send only to your most engaged segment for a few sends.
- Find the cause — a bad list segment, broken authentication or content that annoyed people.
- Resume slowly once the numbers recover.
Mistakes that ruin a warm-up
- Importing an old list and emailing everyone on day one.
- Using a bought or scraped list — it will fail a warm-up and breaks the law in Canada.
- Changing domain to escape a bad reputation. Providers notice, and a new domain starts with no trust.
- Hiding the unsubscribe link, which turns unsubscribers into complainers.
- Sending only promotions. Useful, welcome content gets the engagement you need early.
After the warm-up
Keep the habits that built your reputation: send consistently, keep your list clean, segment by engagement, and avoid sudden huge spikes (for example on Black Friday, ramp up in the weeks before). See how to clean your email list and Gmail and Yahoo sender requirements.
In Reepio
Reepio walks you through adding SPF, DKIM and DMARC for your domain and re-checks the records every day, warning you if one breaks. You can build segments of your most engaged contacts for the first sends, schedule each step of your warm-up, and watch bounces and complaints in every campaign report. Sending pauses automatically if bounce or complaint rates spike, protecting your reputation. Start free.
Frequently asked questions
How long does it take to warm up a new domain?
For most small business lists, two to four weeks of gradually increasing sends is enough. Larger lists or recovery from a damaged reputation can take longer.
Do I need to warm up if my list is small?
If you send a few hundred emails to people who know you, a formal plan isn’t necessary. Still authenticate your domain first and send to engaged subscribers.
Can I use a warm-up tool that sends fake emails?
It’s better to warm up with real emails to real subscribers. Mailbox providers judge how genuine recipients react, and artificial engagement doesn’t replace that.
What should I do if my emails go to spam during warm-up?
Stop increasing volume, send only to your most engaged subscribers for a few sends, check SPF, DKIM and DMARC, and look for a bad list segment before continuing.