How to improve Gmail inbox placement during IP warmup?
Matthew Whittaker
Co-founder & CTO, Suped
Published 19 Jun 2025
Updated 18 Aug 2025
7 min read
Warming up a new IP address for email sending is a critical phase for establishing a strong sender reputation. It's especially crucial when trying to achieve good inbox placement with mailbox providers like Gmail. If your emails land in the spam folder during this period, it can significantly hinder your deliverability long-term.
The goal of IP warmup is to gradually build trust with Internet Service Providers (ISPs). This trust is built by demonstrating consistent, positive sending behavior over time, rather than suddenly sending large volumes of mail. A new IP address (or domain) starts with little to no reputation, and ISPs are inherently cautious about mail from unknown senders to protect their users from spam.
When you're seeing low open rates, for example, under 1% for Gmail, it's a strong indicator that your emails are likely being filtered to the spam folder, even if they are technically 'delivered.' This article explores how to address these issues and improve your Gmail inbox placement during the crucial IP warmup phase.
Strategic IP warmup
A well-structured IP warmup schedule is foundational. It involves incrementally increasing your sending volume to specific mailbox providers over several weeks. The exact schedule depends on your overall sending volume and the recipients you are targeting, but the principle is always to start small and grow steadily.
During warmup, prioritize sending to your most engaged subscribers. These are individuals who have recently opened, clicked, or replied to your emails. Their positive interactions provide strong engagement signals to ISPs, which are vital for building a good sender reputation. Conversely, sending to disengaged or unverified contacts can quickly damage your reputation, as it may lead to bounces, spam complaints, or a lack of engagement, pushing your emails to the spam folder.
Consistency is also key. Avoid sudden spikes or drops in sending volume during your warmup period. Irregular sending patterns can flag your activity as suspicious. Aim for a predictable, gradual increase that allows Gmail and other providers to learn about your legitimate sending habits. It is also wise to understand the best IP and domain warmup strategy for major mailbox providers.
A common IP warming plan starts with sending small volumes daily, then slowly increases the volume week by week. The exact numbers will vary based on your total list size and email frequency.
Day
Gmail Volume (Approx.)
Days 1-3
500-1,000
Days 4-7
1,000-2,500
Week 2
2,500-5,000 daily
Week 3
5,000-10,000 daily
Week 4+
Gradual increase towards full volume
Content and engagement
The content of your emails plays a significant role in how ISPs, especially Gmail, perceive your sending. During warmup, it's best to send simple, high-value content that encourages engagement. Avoid overly promotional language, excessive images, or too many links.
Email content issues can silently hinder your deliverability. Ensure that all links in your emails are consistent with your sending domain to avoid any flags. Large images (over 300KB) and a lack of alt text can also contribute to emails being flagged, potentially leading to Gmail message clipping and a negative user experience, which indirectly affects your sender reputation.
High engagement rates, specifically opens, clicks, and replies, are crucial signals to Gmail that your emails are valued by recipients. Encourage these actions during warmup by sending highly relevant content to your most active users. If recipients manually move your emails from spam to the inbox, this provides a very strong positive signal, helping to reinforce your sender reputation.
Best practices for email content
Text-to-HTML ratio: Maintain a healthy balance. Too many images or complex HTML can trigger spam filters.
Personalization: Use personalization to make emails more relevant and encourage engagement.
Clear calls to action: Make it easy for recipients to interact with your emails.
Consistent branding: Ensure your emails look legitimate and professional.
Monitoring and troubleshooting
Monitoring your IP and domain reputation is vital during warmup. Google Postmaster Tools is an indispensable (and free) resource for this, providing data on your sending IP and domain reputation, spam rates, feedback loops, and delivery errors. Regularly checking these metrics can alert you to potential issues before they escalate.
Keep a close eye on your spam rate and IP reputation in Postmaster Tools. A low open rate coupled with a high spam rate indicates a problem. If your IP reputation is 'red' or 'yellow,' it means your emails are likely not reaching the inbox. Address any issues promptly, as a damaged reputation can be difficult to recover. Understanding the ultimate guide for Postmaster Tools can help you interpret the data.
While Gmail primarily relies on its internal reputation systems, it may use some third-party blocklists (or blacklists) as data sources, rather than for direct blocking. Still, proactively checking if your IP or domain appears on any major public blocklists (or blacklists) is a good practice. If you find your IP or domain listed, identify the cause and request delisting.
Proactive monitoring
Daily checks: Review your Gmail Postmaster Tools data daily during warmup.
Deliverability reports: Analyze reports from your email sending platform for bounce rates and deferrals.
Reactive troubleshooting
High spam rates: Investigate content, list quality, and engagement.
Proper email authentication is the bedrock of deliverability. Ensure your SPF (Sender Policy Framework), DKIM (DomainKeys Identified Mail), and DMARC (Domain-based Message Authentication, Reporting & Conformance) records are correctly configured from day one. These protocols verify that your emails are legitimate and prevent spoofing, which is critical for building trust with Gmail.
Specifically for Gmail, a strict DMARC policy (p=quarantine or p=reject) helps protect your domain from abuse and signals to Gmail that you are serious about email security. If your email service provider (ESP) or marketing platform, such as Braze, uses a third-party sending service like SparkPost, ensure that their sending infrastructure is correctly configured to pass SPF and DKIM authentication for your domain. This ensures proper DMARC alignment.
Another often overlooked aspect is the domain used in your links. It is generally recommended that all links within your email content (tracking links, image links, etc.) are subdomains of your main sending domain. This consistency further reinforces your brand identity and helps establish trust with mailbox providers, preventing potential flags that could arise from misaligned or suspicious link domains.
Always start by sending to your most engaged segments to build positive reputation signals.
Maintain a consistent daily sending volume, gradually increasing it over several weeks.
Monitor your Gmail Postmaster Tools data closely for any dips in reputation or increases in spam rate.
Ensure SPF, DKIM, and DMARC are correctly set up and passing authentication.
Common pitfalls
Sending large volumes to unengaged or unverified lists, leading to high bounce and complaint rates.
Ignoring low open rates during warmup and continuing to send high volumes.
Not checking Google Postmaster Tools regularly for reputation and deliverability metrics.
Having misconfigured email authentication records, such as SPF, DKIM, or DMARC.
Expert tips
If issues persist, consider isolating the problem by comparing performance across different ESPs or IPs.
Remember that Gmail's reputation system is complex and heavily relies on recipient engagement.
Don't solely rely on your ESP to handle all deliverability aspects; proactive monitoring is essential.
Engage in conversations within the email community to learn from others' experiences and insights.
Marketer view
Marketer from Email Geeks says that if you're four weeks into IP warmup and still seeing very low Gmail open rates, something is definitely wrong and waiting it out is not a viable strategy.
2025-07-20 - Email Geeks
Marketer view
Marketer from Email Geeks says that checking email content for HTTP links, images over 300KB, and a lack of alt text can help identify hidden issues.
2025-07-20 - Email Geeks
Conclusion
Improving Gmail inbox placement during IP warmup requires a multifaceted approach focused on building trust and demonstrating legitimate sending behavior. This involves a carefully planned sending schedule, targeting highly engaged recipients, optimizing email content, and diligent monitoring of your sender reputation through tools like Google Postmaster Tools.
Establishing proper authentication (SPF, DKIM, DMARC) and ensuring consistent domain alignment in your links are technical prerequisites that reinforce your legitimacy. Remember that IP warmup is an investment in your long-term email deliverability, so patience, consistent effort, and proactive problem-solving are paramount for success.
Gmail. If your emails land in the spam folder during this period, it can significantly hinder your deliverability long-term.
Google Postmaster Tools is an indispensable (and free) resource for this, providing data on your sending IP and domain reputation, spam rates, feedback loops, and delivery errors. Regularly checking these metrics can alert you to potential issues before they escalate.
Braze, uses a third-party sending service like 
SparkPost, ensure that their sending infrastructure is correctly configured to pass SPF and DKIM authentication for your domain. This ensures proper DMARC alignment.
