What is a good strategy for aggressively warming a new email domain?

Key findings

• Domain vs. IP Warm-up: Even with a warm IP, a new domain needs its own warm-up period to establish its reputation. ISP algorithms assess domain trustworthiness separately.
• Engagement is key: The speed of domain warming is directly tied to user engagement. High open rates, clicks, and replies signal positive intent to ISPs, while low engagement, complaints, or bounces will quickly damage reputation.
• ISP variations: Some ISPs, like Gmail, might be more forgiving with aggressive warming if engagement is strong, while others, such as Microsoft (Hotmail/Outlook.com), often have stricter filters (SmartScreen) and require a more cautious approach, even if IP reputation is good. Refer to strategies for warming with Gmail and Microsoft.
• List quality: While list validation is a good first step, it does not guarantee engagement or active contacts. Sending to unengaged or inactive addresses, even if validated, can harm a new domain's reputation.
• Risk of blocklisting: Aggressive sending can lead to hitting spam traps or generating high complaint rates, resulting in the domain being placed on email blacklists or blocklists. Maintaining a blocklist monitoring program is crucial during this period.

Key considerations

• Gradual increase, even if aggressive: While aiming for speed, a daily or weekly progressive increase in volume is still advisable. A sudden high volume can trigger spam filters.
• Segment for engagement: Start by sending to your most engaged contacts first. These are recipients who have recently opened or clicked your emails. This helps build a positive sending history.
• Content quality: Ensure your content is highly relevant and valuable to encourage opens and clicks, further boosting your domain's reputation.
• Monitor deliverability metrics: Closely watch open rates, click-through rates, bounce rates, and complaint rates. Use ISP postmaster tools for insights into your domain's performance.
• Authentication: Ensure your domain has proper SPF, DKIM, and DMARC records configured from day one. This foundational step is critical for deliverability. Consider our simple guide to DMARC, SPF, and DKIM.

Key opinions

• Defining aggressive: What constitutes an aggressive warm-up varies, but marketers aiming for 1.7 million emails in 1-2 weeks consider this a very fast pace.
• Shared IPs vs. new domain: Marketers note that using a large pool of shared IPs could potentially support faster domain warming, but a new domain on its own still faces a learning curve.
• Engagement is non-negotiable: The ultimate factor in domain warming speed is user engagement. ISPs will only ramp up delivery as fast as the domain proves it's sending wanted mail.
• ISP differences matter: Gmail is generally perceived as more amenable to faster warming than other providers like Hotmail (Microsoft), which often employs stricter SmartScreen filters that can junk messages even with good IP reputation.

Key considerations

• Domain age and distribution: These factors significantly impact how quickly a domain can be warmed. A truly new domain will always have a harder time than one with some history.
• List activity: Simply validating a list (e.g., 1.7 million contacts) is not enough. Marketers need to understand how many contacts are extremely active recently and focus on those for the initial aggressive ramp-up. You can find out more about warming a domain for cold contacts here.
• Opt-in status: All contacts must be explicitly opt-in to avoid compliance and deliverability issues. This is a fundamental requirement for successful warming.
• Proactive support: While not always effective for domain warming, some marketers suggest contacting ISP support (like Hotmail's) for proactive communication, though preemptive accommodations are rarely granted for domain specific issues.
• Monitoring tools: Marketers rely on tools like Google Postmaster Tools and SNDS for Microsoft to track domain health, but note that green signals in SNDS don't always prevent SmartScreen filtering.

Key opinions

• Pace is set by ISPs: Experts agree that the maximum speed at which a domain can be warmed is dictated by the mailbox providers' (MBP) learning algorithms, not by sender volume desires.
• Engagement is paramount: The quality of engagement is far more critical than the quantity of sends. High opens, clicks, and low complaints from a highly active segment of your list are essential.
• List hygiene is crucial: A "validated" list is insufficient. Experts advise focusing on recently active and opt-in contacts to avoid spam traps and unengaged recipients.
• Reputation is delicate: Pushing too hard too fast can irreversibly damage a new domain's reputation, leading to long-term deliverability problems that are difficult to recover from. Learn more about recovering domain reputation.

Key considerations

• ISP-specific nuances: Experts advise understanding that each ISP (e.g., Gmail, Microsoft, Yahoo) has its own algorithms and tolerance for new sending domains. A strategy that works for one may not work for another.
• SmartScreen's role: Microsoft's SmartScreen filtering can place new domain mail in junk even if IP reputation is good. It requires proof of recipient desire for messages from that domain, which comes from sustained engagement.
• Long-term sender reputation: Focus on building a sustainable sender reputation. Aggressive tactics might yield short-term volume, but they can undermine future deliverability if not managed carefully. Understanding your email domain reputation is key.
• Monitor and adapt: Continuous monitoring of deliverability metrics, feedback loop reports, and ISP postmaster tools is essential. Be prepared to adjust sending volume based on performance. For more, see Kickbox's guide on pre-warming steps.

Key findings

• Gradual volume increase: Documentation consistently recommends starting with low volumes and incrementally increasing them over days or weeks, allowing ISPs to assess the new domain's sending behavior.
• Engagement-focused sending: Prioritize sending to highly engaged subscribers who are most likely to open and click. This positive interaction helps build sender reputation with ISPs. See more on increasing email click-through rates.
• Consistency is key: Maintain a steady sending volume throughout the warm-up period, rather than erratic spikes, to help ISPs build a reliable profile of your domain.
• Monitor and react: Documentation advises vigilant monitoring of deliverability metrics (bounces, complaints, blocklistings) and adjusting sending volume as needed to prevent adverse reputation impacts.
• Authentication standards: Proper implementation of email authentication protocols like SPF, DKIM, and DMARC is fundamental for a new domain to establish legitimacy. Our guide on DMARC policy transitions can assist.

Key considerations

• Avoid purchased lists: Documentation explicitly warns against sending to purchased, rented, or old lists, as they often contain spam traps and unengaged users that will quickly damage a new domain's reputation.
• Segment by ISP: Some documentation suggests warming up to specific ISPs individually, as their systems learn at different rates and have different thresholds.
• Feedback loops: Sign up for and actively monitor ISP feedback loops to promptly identify and address complaint rates, which are crucial indicators of domain health.
• Patience is a virtue: While aggressive warming is desired, documentation implies that rushing the process beyond what ISPs deem acceptable will likely result in a degraded sender reputation and reduced inbox placement. A comprehensive guide on Twilio SendGrid's IP warm-up principles applies broadly to domain warming too.