Summary
When warming up new IPs, the consensus from experts, marketers, and documentation emphasizes that there is no one-size-fits-all approach. The choice between warming up per domain or per MX depends on factors like sending volume, available resources, and specific goals. Warming up per domain is generally simpler, especially for smaller senders. However, for ESPs or high-volume senders, warming up per MX might be more efficient, although it requires more effort. Regardless of the chosen method, focusing on sending to engaged users, maintaining good list hygiene, implementing proper authentication (SPF, DKIM, DMARC), and continuous monitoring of deliverability metrics are crucial for building a positive sender reputation and ensuring optimal deliverability. Furthermore, separating transactional and marketing email streams is recommended to protect transactional deliverability.
Key findings
- No Universal Method: IP warming strategy (per domain vs. per MX) depends on specific circumstances; no single approach is universally superior.
- Engagement Focus: Sending to engaged users is crucial for building a positive sender reputation, irrespective of the warming method.
- Hygiene and Authentication: Maintaining good list hygiene (removing invalid addresses) and implementing proper email authentication (SPF, DKIM, DMARC) are essential.
- Monitoring is Key: Continuous monitoring of deliverability metrics (bounce rates, complaint rates, spam rates) is crucial for adapting the warm-up strategy.
- Per-Domain Simplicity: Warming up per domain is generally simpler and sufficient for most senders, especially those with lower sending volumes.
- Per-MX Efficiency: Warming up per MX can be more efficient for ESPs and high-volume senders, but it requires more effort and technical expertise.
Key considerations
- Sending Volume: Assess your sending volume when deciding between warming up per domain and per MX.
- Resource Availability: Evaluate available technical resources and expertise, as warming up per MX requires more technical knowledge and management.
- List Segmentation: Segment your email list by engagement level and prioritize sending to the most active subscribers during the initial warm-up phase.
- Authentication Setup: Ensure SPF, DKIM, and DMARC are correctly configured before starting the warm-up process.
- Deliverability Monitoring: Regularly monitor deliverability metrics to identify and address any issues promptly, adjusting the warm-up strategy as needed.
- Separate IP Streams: Consider using separate IP addresses for transactional and marketing emails to prevent deliverability issues with critical transactional messages.
- Data-Driven Adjustments: Be prepared to adapt the warm-up strategy based on the deliverability data and feedback received from ISPs.
What email marketers say
9 marketer opinions
When warming up new IPs, email marketers suggest that the choice between warming up per domain versus per MX depends on factors like sending volume, available resources, and specific goals. Warming up per domain is often simpler, especially for smaller senders. However, for ESPs or high-volume senders, warming up per MX might be more efficient. Regardless of the method, focusing on sending to engaged users, maintaining good list hygiene, and implementing proper authentication (SPF, DKIM, DMARC) are crucial for building a positive sender reputation and ensuring optimal deliverability. Monitoring deliverability metrics and adjusting the warm-up strategy based on data are also key.
Key opinions
- Per Domain vs. MX: Warming up per domain is simpler for smaller senders; per MX can be more efficient for high-volume senders or ESPs.
- Engagement Focus: Sending to engaged users is crucial for building a positive sender reputation regardless of the warm-up method.
- List Hygiene: Maintaining a clean email list by removing invalid addresses is essential for effective IP warming.
- Authentication: Implementing SPF, DKIM, and DMARC is vital for establishing trust with ISPs.
- Gradual Increase: Gradually increasing sending volume in smaller batches helps establish a consistent sending pattern.
Key considerations
- Sending Volume: Consider the volume of emails you send when deciding between per-domain and per-MX warming.
- Resources: Assess the time and resources available for managing the warm-up process. Per-MX requires more expertise.
- Engagement Segmentation: Segment your email list by engagement level to prioritize sending to the most active subscribers first.
- Deliverability Monitoring: Continuously monitor your deliverability metrics (bounce rates, complaint rates) to identify and address any issues promptly.
- Separate IPs: Consider using separate IP addresses for marketing and transactional emails to protect transactional deliverability.
Marketer view
Email marketer from EmailVendorSelection explains that a good list and email setup with a solid sender reputation is the best way to warm-up an IP address. They share it is a waste of time and money warming up a list of invalid email addresses.
22 Dec 2024 - EmailVendorSelection
Marketer view
Email marketer from Mailjet explains that warming up per domain is often simpler for smaller senders. They share that focusing on sending to engaged users helps build a positive reputation regardless of the method.
24 Mar 2022 - Mailjet
What the experts say
3 expert opinions
Experts generally agree that there's no single 'best' approach for IP warming, but rather a range of strategies depending on specific circumstances. Warming per-domain can be sufficient for a rough ramp-up, as per-MX requires more effort. However, good list hygiene, engagement, proper authentication (SPF, DKIM, DMARC), and continuous monitoring are consistently emphasized as critical factors overriding specific domain vs. MX strategies. Adjusting the warm-up strategy based on deliverability data and focusing on positive sending reputation through engaged subscribers are also key.
Key opinions
- No One-Size-Fits-All: There's no universally superior method for IP warming; strategies depend on specific contexts.
- Engagement Matters: Focusing on sending to engaged subscribers is crucial for building a positive sender reputation.
- Monitoring is Key: Continuously monitoring deliverability metrics is essential for adjusting the warm-up strategy.
- Basic Hygiene: List hygiene and proper authentication are more important than choosing between per-domain or per-MX.
- Per-Domain Sufficiency: Warming per-domain is often sufficient if aiming for a rough ramp-up.
Key considerations
- Effort vs. Precision: Weigh the effort required for per-MX warming against the need for precise control.
- Data-Driven Adjustments: Be prepared to adjust your warm-up strategy based on deliverability data.
- List Quality: Prioritize list hygiene and engagement to ensure a positive sender reputation.
- Authentication Setup: Ensure proper authentication (SPF, DKIM, DMARC) is in place before starting the warm-up process.
- Long-Term Reputation: Focus on building a sustainable, positive sender reputation rather than just quick wins.
Expert view
Expert from Spam Resource explains that it's essential to monitor deliverability and adjust the warm-up strategy as needed. They suggest focusing on building a positive sending reputation by sending to engaged subscribers.
22 Jun 2023 - Spam Resource
Expert view
Expert from Email Geeks responds that warming up per-MX takes more effort, and since you are aiming for a rough ramp-up, warming up per-domain is sufficient.
20 Jun 2024 - Email Geeks
What the documentation says
3 technical articles
Email service documentation consistently emphasizes gradual IP warming, consistent volume, engagement metrics, and good sender reputation as crucial for successful deliverability. While not explicitly detailing per-domain vs. per-MX strategies, they underscore the importance of overall sending health, monitoring sending limits, minimizing bounces and complaints, and ensuring proper authentication to avoid spam filters and build trust with ISPs.
Key findings
- Gradual Warm-up: Increasing sending volume gradually is essential for building a positive sender reputation.
- Engagement Metrics: Consistent volume and high engagement are crucial for maintaining sending health.
- Sender Reputation: Maintaining a good sender reputation is paramount throughout the warm-up process.
- Authentication Importance: Proper authentication is essential to avoid spam filters and build trust with ISPs.
- Limit Monitoring: Monitoring sending limits is crucial to avoid deliverability issues.
Key considerations
- Overall Sending Health: Focus on overall sending health rather than solely on per-domain vs. per-MX strategies.
- Bounce and Complaint Rates: Minimize bounce and complaint rates to improve sender reputation.
- ISP Trust: Build trust with ISPs through consistent, engaged sending patterns.
- Authentication Setup: Ensure all authentication methods are correctly configured before starting the warm-up process.
- Long-Term Strategy: View IP warming as a long-term strategy for sustainable deliverability.
Technical article
Documentation from Twilio SendGrid explains that IP warming involves gradually increasing sending volume to build a positive reputation with ISPs, emphasizing consistent volume and engagement metrics. They don't directly specify per-domain vs. per-MX, but imply focusing on overall sending health.
24 Dec 2021 - Twilio SendGrid
Technical article
Documentation from Google suggests ensuring you have all authentication methods in place. They share that a high Spam Rate might result in your email being delivered to your recipients’ Spam folders, or might even be blocked completely.
18 Mar 2025 - Google
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