Summary
When introducing a new sending domain while retaining an established, warmed IP address, the primary focus of a warm-up shifts from IP reputation to building the domain's own sender reputation. While the warmed IP provides a foundational level of trust, major mailbox providers like Gmail and Microsoft closely monitor domain-level engagement and authentication, necessitating a careful, gradual approach to volume increases for the new domain. This process aims to demonstrate legitimate sending patterns and positive engagement from the outset, mitigating the risk of deliverability issues.
Key findings
- Domain-focused warmup: The existing warmed IP provides a strong foundation, but the new domain still requires a dedicated warm-up to build its unique sender reputation with internet service providers (ISPs).
- Controlled throttling: A gradual increase in sending volume for the new domain is crucial, similar to an IP warm-up, to avoid triggering spam filters due to sudden high volumes from an unknown sender identity.
- Major mailbox provider emphasis: While some smaller ISPs may be less stringent, major providers like Gmail, Microsoft, and Verizon Media Group (VMG) are highly attentive to new domain reputations. Focusing your warm-up efforts on these providers will generally benefit overall deliverability.
- Reputation components: Gmail, for example, evaluates a combination of IP, SPF, and DKIM domain values to assess sender reputation, reinforcing the need for domain-specific warming.
Key considerations
- Gradual volume ramp-up: Implement a disciplined schedule to slowly increase the daily sending volume from the new domain. This shows ISPs that you are a legitimate sender building a positive history.
- Engagement monitoring: Closely monitor engagement metrics like open rates, click-through rates, and complaint rates for the new domain. Positive engagement signals are critical for building trust. Our guide on Google Postmaster Tools can help with this.
- Segmentation: While a full breakdown by subscriber domain may not be strictly necessary for a warmed IP, starting with the most engaged segments of your list can bolster initial reputation.
- Authentication setup: Ensure that your new sending domain has properly configured SPF, DKIM, and DMARC records. These are fundamental to proving your legitimacy. More information on domain and IP warm-up strategies can be found in authoritative guides.
What email marketers say
Email marketers widely agree that while a new domain on a warmed IP doesn't require the same intensive warm-up as a completely new IP and domain pair, it still demands a measured approach. The consensus suggests focusing on gradual volume increases and closely monitoring performance, especially with major mailbox providers. Marketers often observe that ISPs, particularly the larger ones, are more concerned with domain reputation than smaller players, making a targeted warm-up strategy essential even when the IP is mature.
Key opinions
- Domain warm-up is necessary: Even with a pre-warmed IP, a new sending domain needs its own warm-up phase to establish trust.
- Controlled throttling is key: Instead of a full, multi-week IP warm-up, a controlled throttle for initial deployments of the new domain is often sufficient.
- Microsoft can be challenging: Domain changes can be complicated, especially when sending to Microsoft recipients, requiring careful attention. For more insights on this, refer to resolving IP warming issues with Microsoft.
- Focus on major ISPs: Gmail, Microsoft, and Verizon Media Group are the primary providers that demand rigorous domain warm-up, and successfully warming for them generally ensures broader deliverability.
Key considerations
- Gradual volume increase: Start with a low volume and slowly increase it for the new domain, continually monitoring performance. This is aligned with general IP warming advice.
- Monitor with postmaster tools: For Gmail, utilize Google Postmaster Tools to track the new domain's reputation. For other providers, watch your open rates and overall inbox placement. Learn more about improving domain reputation.
- Audience size matters: For smaller lists (e.g., 50k subscribers), a less aggressive warm-up may be feasible compared to much larger audiences (e.g., 1.5 million).
- Geographic considerations: While major ISPs often cover global deliverability, be aware that local anti-spam systems in specific countries might also be sensitive to new, un-warmed domains.
Marketer view
Email marketer from Email Geeks suggests that a controlled throttle for the first deployment should suffice when switching a sending domain on an existing warmed IP, without needing a full IP warm-up strategy.
Marketer view
Email marketer from Email Geeks indicates that a more significant warm-up is typically reserved for scenarios involving both a new domain and a new IP, where a multi-week, domain-specific approach is often implemented.
What the experts say
Deliverability experts confirm that warming up a new domain, even on a pre-warmed IP, is a critical step, primarily due to the stringent requirements of major mailbox providers. They emphasize that while the IP carries some existing reputation, the domain's independent reputation needs to be built. This involves careful volume scaling and continuous monitoring, with particular attention paid to how providers like Gmail and Microsoft assess sender identity, which includes a combination of IP, SPF, and the DKIM 'd=' value.
Key opinions
- Major ISPs are the priority: Warm-up efforts should primarily target Gmail, Microsoft, and Verizon Media Group because they are the most discerning, and successfully warming for them will generally satisfy other providers.
- Domain reputation is distinct: Even with a warm IP, the new domain itself needs to establish its own trust and reputation.
- Sensible starting volumes: Starting with a few thousand emails, rather than very small numbers, is a more practical and effective approach for domain warm-up.
- Combined reputation factors: Gmail, in particular, combines the IP, SPF, and DKIM 'd=' value to form a sender's reputation, underscoring why domain warm-up is essential even with a pre-warmed IP.
Key considerations
- Monitor domain-related metrics: Beyond just IP, track specific domain-related metrics to gauge progress and identify any potential issues early in the warm-up process.
- Adjustments impact reputation: Any changes to sending configurations, including switching domains, can affect your established sender reputation. This highlights the importance of a structured warm-up. This is also covered in our best practices for switching to a new sending domain guide.
- Patience is a virtue: While not as long as an IP warm-up, establishing a new domain's reputation still takes time and consistent positive sending behavior. Consider what Twilio SendGrid advises on IP warm-up, which can be broadly applied to domain warming.
- Understanding ISP policies: Dive into specific ISP requirements for warm-up. For instance, knowing Gmail and Microsoft's strategies can greatly optimize your approach.
Expert view
Expert from Email Geeks explains that a client successfully warmed up a new domain for Gmail by performing three sends a day over five to six days, ultimately reaching 1.5 million emails.
Expert view
Expert from Email Geeks states that warm-up is fundamentally a concern primarily for major email providers such as Gmail, Microsoft, and Verizon Media Group.
What the documentation says
Official documentation from various email service providers and deliverability platforms consistently emphasizes the importance of domain warm-up, even when using an already warmed IP. They highlight that while IP reputation contributes, domain reputation is a distinct and equally vital factor for inbox placement. The core principle remains a gradual increase in sending volume, focusing on engaged subscribers, and diligently monitoring performance to build a positive sender identity for the new domain over time.
Key findings
- Progressive volume increase: Documentation across platforms advises gradually increasing sending volume from a new domain to avoid deliverability issues, even with a warm IP.
- Domain reputation building: The explicit goal of domain warming is to improve the new domain's reputation with ISPs.
- Engagement is key: Using highly engaged subscriber segments during warm-up is a best practice to signal positive sending behavior to mailbox providers.
- Long-term strategy: The warm-up period can range from several weeks, during which consistent monitoring is crucial.
Key considerations
- Consistent sending: Maintain consistent sending practices throughout the warm-up period for the new domain.
- Authentication setup: Ensure all email authentication protocols (SPF, DKIM, DMARC) are correctly configured for the new domain from day one. You can find more information about email authentication and IP warm-up.
- Choose the right process: Select a warming process that aligns with your sending volume and list characteristics to build a strong initial sender reputation effectively.
- Monitor deliverability: Continuously monitor inbox placement and reputation metrics to adapt your strategy as needed. Our guide to understanding your email domain reputation provides further detail.
Technical article
Documentation from Resend explains that warming up a domain or IP involves progressively increasing your sending volume to effectively avoid common deliverability issues.
Technical article
Documentation from Klaviyo advises that choosing the correct warming process is essential to establish a strong initial sender reputation, ensuring favorable treatment by inbox providers.
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