Unlock Your Mailchimp Success: A Step‑by‑Step Guide to Domain Warm‑Up

Before you send your first campaign, it’s crucial to build trust with inbox providers. That starts by warming up your domain with a step-by-step process that helps your emails land where they belong, the inbox.

When you send from a new domain or IP, inbox providers like Gmail and Outlook don’t know if you’re a trustworthy sender or a potential spammer. They watch how recipients respond—do they open, click, ignore, or mark your email as spam? Starting slow with your most engaged contacts helps you build a strong sender reputation and improves your chances of avoiding the junk folder. Warming your domain builds trust with ISPs. 

Here’s a 4-week warm-up strategy to help you hit key deliverability benchmarks: average open rates above 30%, click-through rates above 1%, and minimal bounces, complaints, and unsubscribes. Strong early performance earns you better inbox placement going forward.

Foundations for deliverability

Before you send a single email, get these essentials in place. Each one helps prove you're a legitimate sender and sets the stage for strong deliverability.

Get clear, verifiable permission

Sending to people who didn’t sign up for your emails is the fastest way to damage your reputation. Make sure every contact you’ve imported has explicitly opted in to receive marketing emails from you. This protects your sender reputation—and it's required under Mailchimp’s Terms of Use.

Authenticate your sending domain

Domain authentication acts like a digital ID for your emails, proving you are who you say you are. It shows inbox providers that your emails are legitimate and not spoofed or forged. When you authenticate your domain, your messages are more likely to get delivered and look more professional in the inbox.

To do this, set up DKIM, SPF, and DMARC for your sending domain. Mailchimp walks you through this process in your account settings. Once you authenticate, you’ll also remove the “via mcsv.net” or “on behalf of” labels that can make emails look suspicious.

Need help? Explore our guide: About Email Domain Authentication

Week 1: Establish early engagement

Your first sends matter most. Start with a small, highly engaged segment of people who are most likely to open, read, and click. If you don’t have engagement data yet, lean on recent opt-ins or known loyal customers.

High engagement segment: 5-10% of your total list

Total send volume: ~5-10%

Campaign ideas: Send a welcome message, a valuable piece of content, or a limited-time offer to prompt engagement.

Actions in Mailchimp:

• Use Campaign Manager to schedule and organize your sends.
• Day 1–3: Send your first campaign to your initial 5% segment.
• Day 4–7 (optional): If Campaign 1 performs well, send to another highly engaged 5% segment.

What to monitor:

Even though campaigns are sent weekly, you should monitor performance daily. Inbox providers evaluate sender reputation based on short-term patterns, so it's important to catch and respond to changes quickly.

• Are open rates above 30%? Are click-through rates above 1%?
• Are bounces, unsubscribes, and complaints staying below 1%?
• If metrics fall short, pause before sending again. Review your content, subject line, and audience selection. Make adjustments and try again.

Week 3: Build momentum

If your first 2 weeks have delivered strong engagement and low complaint rates, you can start scaling more significantly. Continue prioritizing segment quality over raw volume.

Somewhat engaged segments: +20% of your total list

Total send volume: ~65–70%

Actions in Mailchimp:

• Day 15–17: Send Campaign 5 to the next 20% segment.
• Day 18–21: Send Campaign 6 to a different 20% segment.

Campaign reminder: Stick with content that reinforces your value, such as expert advice, timely updates, or personalized offers.

What to monitor:

• Are your engagement metrics holding steady?
• Are negative signals (bounces, unsubscribes, complaints) still low?
• Use this week to confirm your reputation is scaling with your volume.

Maintain your deliverability after the warm-up

Warming up your domain is just the start. Deliverability depends on the choices you make every time you hit send. Here's how to stay in good standing with inbox providers.

Monitor your performance. Check campaign results regularly. If open rates dip or spam complaints rise, investigate and adjust quickly.

Keep your list clean. Archive or re-engage contacts who haven’t engaged in a while. Continuing to email unresponsive contacts can hurt your reputation.

Send with relevance. Avoid one-size-fits-all messages. Use Mailchimp’s segmentation tools to tailor content based on behavior, interests, or past purchases.

Include reminders and easy opt-outs. Always include a clear permission reminder in your footer. And make your unsubscribe link easy to find. It's better for someone to opt out than to mark your email as spam.

Keep applying these best practices to protect your sender reputation and ensure your emails continue reaching the inbox.