Warming up a new domain and IP is crucial to ensure high deliverability and maintain a positive sender reputation. Mailbox providers often have a low acceptance rate for emails from new domains and IPs, making a slow and steady approach essential. This guide outlines a prioritized strategy and key best practices for effectively warming up your domain, leading to improved engagement and higher open rates.

Prioritized Warm-Up Strategy

To avoid low open rates and a drop in reputation, it's vital to prioritize your segments during the ramp-up process. This prioritized approach ensures you are sending emails to users most likely to engage positively, building a strong foundation for your domain's reputation.

Follow this prioritized sequence to target the most engaged users first, optimizing your sender reputation and maximizing early delivery success.

1. Recent email openers (Last 30–90 days)
   • Target: Users who have recently and consistently opened your emails.
   • Strategy: Begin by targeting the last 30-day cohort for immediate, low-risk positive feedback. After being utilized, expand the audience to include openers from the last 90 days.
2. Recent app/site engagers (Last 15–30 days)
   • Target: Users who have actively engaged with your application or website within the defined period.
   • Strategy: Their recent brand interaction makes them reliable candidates for early inclusion in the warm-up flow.
3. Recent high-value converters (Purchasers of the last 30 days)
   • Target: Customers who have completed a recent transaction.
   • Strategy: Their purchase history correlates with a high likelihood of opening emails, which contributes positively to sender metrics.
4. Recent opt-ins (New users of the last 30 days)
   • Target: Newly opted-in users who have recently joined the audience.
   • Strategy: Introduce these new subscribers into the campaign flow gradually.
5. Broader audience (Remaining users)
   • Strategy: Include your wider audience segments only after a strong, positive sender reputation has been established with the prioritized segments above.

Key Best Practices for Domain Warm-Up

Start Slow and Steady

Start the warm-up process by sending a low-volume email to your most engaged users. This measured approach helps mailbox providers recognize your domain as legitimate and trustworthy,  building domain/IP reputation based on observed recipient interaction.

Send Personalized Event-Triggered Campaigns

Personalized campaigns, especially event-triggered ones, have higher engagement rates. This positive interaction signals to mailbox providers that your emails are valuable to recipients.

For use cases in e-commerce lifecycle marketing campaigns, refer to Customer Lifecycle Campaigns.

Go Slow in the First 7-10 Days

The initial 7–10 days of the warm-up process are critical. During this phase, maintain a strictly gradual increase in email volume.

Performance Drop Contingency

If a decline in delivery rates, open rates, or overall reputation is observed, take the following immediate corrective actions:

1. Pause and investigate: Immediately pause the ramp-up for 2 days to allow the IPs to rest and facilitate investigation.
2. Template testing: To determine if the content is contributing to the performance drop, test with different email templates. Conduct inbox placement tests with the revised templates.
3. Restrict sending: Restrict future sending only to highly engaged users (for example, users who have opened emails at least twice in the last 60 days).
4. Resume slowly: Review the domain reputation and resume the sending process at a very slow pace.

Vary Your Email Content

Avoid sending the same email content repeatedly throughout the ramp-up process, as Internet Service Providers (ISPs) may flag repetitive messaging as potential spam. You can:

• Continuously change your email content and refrain from sending identical messages to the same users.
• Utilize A/B testing to introduce content variations, which can support content diversification during the warm-up phase. For more information, refer to the Manual Multivariate Experiment.
• Utilize locale-specific variations (different languages, currencies, or time zones) as a way to vary content.

Increase Pace Based on Performance

While the standard ramp-up plan follows a medium-to-high pace, you must adjust the sending volume based on observed performance.

• Standard ramp-up plan of MoEngage follows a medium-high pace, with a gradual volume increase.
• Determine the optimal email sending increment pace for your brand through testing and adhere to it.
• Make sure not to increase volume when negative signals are present (for example, high spam complaints, rate-limiting, spam placement, low delivery, or a drop in open rates).

Stabilize Reputation Post-Ramp-Up

After the initial warm-up, allow your domain's reputation to stabilize for a minimum of two months at your general sending volume and frequency. You must monitor performance proactively throughout this period.

A stable reputation is characterized by:

• Reliable delivery: Consistent delivery without any rate-limiting.
• Consistent engagement: Good and steady open rates across all major mailboxes. (For new senders, apply for pre-emptive support and monitor closely, as providers like Outlook may initially place emails in spam.)
• Low error rates: Low hard bounce and spam complaint rates. Complaints must remain below the strict threshold of 0.1%.
• High domain authority: A strong overall domain reputation score.

Inactivity Protocol

If email sending has been paused for more than two weeks, the associated IPs lose their warmed-up status. Resuming high volumes immediately after a pause can significantly harm your sender reputation; therefore, consult with the EDC team before resuming activity. The recommended next steps are:

• Target engaged users: Send two email campaigns targeting email openers from the last 60 days and App/Site openers from the last 5–10 days.
• Raise a support ticket with the EDC team for guidance and assessment.