Why is Gmail rate limiting my marketing and transactional emails after a period of low sending volume?
Michael Ko
Co-founder & CEO, Suped
Published 12 Aug 2025
Updated 18 Aug 2025
8 min read
Dealing with email rate limiting from Gmail can be incredibly frustrating, especially when your sending volume has been consistently low. You might wonder why your perfectly legitimate marketing and transactional emails are suddenly being delayed or blocked, seemingly out of the blue. It’s a common scenario that many senders encounter, and it often boils down to how mailbox providers interpret your sending patterns and maintain sender reputation.
The core of the problem lies in the perceived inconsistency of your email volume. Mailbox providers, including Gmail, prefer a steady, predictable sending flow. If you send infrequently, even large, but historically similar, volumes can trigger their spam detection systems because the pattern deviates from their expected baseline for your sender reputation. This can lead to a variety of issues, from delays to outright blocks, impacting both your marketing campaigns and crucial transactional messages.
I've seen many instances where a significant gap in sending, followed by a large volume send, results in rate limiting. It's like a cold engine, it needs to be warmed up before it can run at full capacity. Understanding the nuances of email throttling and how mailbox providers, like Gmail, safeguard their systems is key to overcoming these challenges and ensuring your emails consistently reach the inbox.
Understanding Gmail's rate limiting and bounce messages
When Gmail rate limits your emails, you'll typically see bounce messages that provide clues about the problem. A common one is the 4.7.28 Gmail has detected an unusual rate of mail originating from your SPF domain... To protect our users from spam, mail sent from your domain has been temporarily rate limited error. This is a deferral, meaning Gmail isn't rejecting your email outright, but rather delaying it because your sending pattern appears suspicious relative to your established history.
Another bounce message you might see, especially if your Email Service Provider (ESP) times out before retrying, is 4.4.7 (delivery time expired). This indicates that your ESP couldn't deliver the message within its configured retry window, often due to persistent deferrals from the recipient server, like Gmail, rate limiting your sends. It's crucial to distinguish between true rejections and these deferrals, as they point to different underlying issues.
One of the primary reasons for this unusual rate of mail detection by Gmail is a concept known as IP warming (or lack thereof). When an IP address or domain has low sending volume for an extended period, its established reputation can cool down. A sudden spike in volume after such a cool-down period can look like a malicious actor has taken over your sending infrastructure, leading Gmail to implement rate limits to protect its users from potential spam.
The critical role of sender reputation and consistency
Your sender reputation is a complex score that mailbox providers, including Google, assign to your sending IP address and domain. This reputation dictates how readily your emails are accepted. When you have long periods of low sending volume, Gmail's algorithms might not have enough recent positive data points to trust a sudden surge of mail. This leads to them being cautious and rate limiting your sends.
It’s important to remember that reputation can leak between parent domains and subdomains. So, if a marketing send from a subdomain experiences high bounce rates or spam complaints, it can negatively impact the reputation of your main domain, affecting crucial transactional emails sent from it. This interdependency means all sending practices must be carefully managed across your entire domain.
To gain insights into your domain's health and potential issues, regularly check Google Postmaster Tools (GPT). This free service provides detailed dashboards on your IP and domain reputation, spam rates, delivery errors, and authentication status. It’s an invaluable resource for diagnosing Gmail-specific deliverability problems.
The primary strategy to recover from Gmail rate limiting after low sending volume is to rewarm your IP address and domain. This involves gradually increasing your sending volume over time to rebuild a positive reputation with mailbox providers. Start with smaller, highly engaged segments of your audience and slowly ramp up the volume. This process tells Gmail that your sending is legitimate and consistent.
To prevent future rate limiting, aim for consistent and regular sending, even if it's low volume. Instead of sending one large blast every few months, consider smaller, more frequent sends, such as monthly newsletters or transactional updates. This keeps your IP and domain warm and active in the eyes of mailbox providers. Additionally, segmenting your audience and sending targeted content can improve engagement and reduce the likelihood of complaints, which further supports your sender reputation.
Beyond warming, maintaining a clean and engaged email list is paramount. Regularly remove inactive subscribers and hard bounces to reduce your exposure to spam traps and invalid addresses. Gmail pays close attention to how recipients interact with your emails. High engagement signals legitimacy, while low engagement or high complaint rates can quickly degrade your reputation and trigger rate limits.
Technical considerations and best practices
One effective technical strategy is to separate your email streams. Dedicate specific subdomains and potentially separate IP addresses for marketing emails and transactional emails. This way, if a marketing campaign (which tends to have more variable engagement) faces deliverability challenges, it won't impact the crucial deliverability of your transactional emails, such as password resets or order confirmations. For example, marketing.yourdomain.com for promotions and trans.yourdomain.com for alerts and receipts.
It's also critical to understand your bounce messages in detail. Bounce codes provide specific reasons for non-delivery and are invaluable for troubleshooting. Many ESPs, like Salesforce Marketing Cloud (SFMC), provide a _Bounce Data View that allows you to extract full, unredacted bounce messages. This level of detail helps pinpoint whether the issue is a temporary rate limit (like the 4.7.28) or something else entirely.
Finally, ensure your authentication protocols are impeccable. Correct SPF, DKIM, and DMARC configurations are foundational to building and maintaining trust with Gmail and other mailbox providers. Without these, even well-behaved sending patterns can be flagged as suspicious. Gmail's recent changes emphasize these requirements more than ever for bulk senders.
Marketing emails
Content: Promotions, newsletters, sales offers.
Audience: Larger lists, potentially less engaged segments.
Impact on reputation: Higher risk for complaints or bounces.
Audience: Highly engaged individuals expecting the email.
Impact on reputation: Generally positive, critical for core business.
Views from the trenches
Best practices
Maintain a consistent sending volume, even if it's low, to keep your IP and domain warm and active.
Implement a gradual re-warming process for your IP and domain after any prolonged period of inactivity.
Segment your email lists and send targeted content to improve engagement and reduce complaint rates.
Separate marketing and transactional email streams using distinct subdomains or IP addresses.
Routinely monitor your sender reputation using Google Postmaster Tools and analyze bounce messages for insights.
Common pitfalls
A sudden, large increase in sending volume after a long period of low activity can trigger rate limits.
Ignoring bounce messages or failing to understand their specific error codes will hinder troubleshooting.
Failing to separate marketing and transactional emails can lead to critical business communications being blocked.
Not regularly cleaning your email list of unengaged or invalid addresses can lead to spam trap hits and blocklistings.
Assuming that a previously good sending reputation will persist indefinitely without consistent, positive sending.
Expert tips
Always get the full, unredacted bounce messages; they are your primary diagnostic tool.
Understand that domain reputation can leak between subdomains, so a problem on one can affect others.
Gmail's detection of 'unusual rate of mail' is a direct signal of an unexpected volume pattern, requiring a re-evaluation of your sending cadence.
If your ESP lists deferrals as 'technical bounces' or 'delivery time expired', it's likely due to mailbox provider throttling.
Google's sender requirements are evolving, and domain reputation issues, especially related to volume consistency, are becoming more prevalent.
Expert view
Expert from Email Geeks says that getting more information on the cause of Google blocks, such as the actual bounce message, is the first critical step.
2025-02-03 - Email Geeks
Expert view
Expert from Email Geeks says that if Google tells you the problem was 'unexpected volume', it's because you sent more mail than they anticipated, leading to rate limiting.
2025-02-03 - Email Geeks
Restoring and maintaining your Gmail deliverability
Being rate limited by Gmail after a period of low sending volume is a clear signal that your sending patterns are not aligning with their expectations for your domain's reputation. It’s a common challenge, but one that can be effectively managed with the right approach. Focus on understanding the specific bounce messages, monitoring your sender reputation diligently, and implementing strategies that prioritize consistent sending and list hygiene.
By proactively re-warming your IP and domain if necessary, maintaining a steady sending cadence, and segmenting your email streams, you can rebuild trust with Gmail. This comprehensive approach will help ensure your marketing and transactional emails achieve optimal deliverability, hitting the inbox consistently and reliably.
Gmail can be incredibly frustrating, especially when your sending volume has been consistently low. You might wonder why your perfectly legitimate marketing and transactional emails are suddenly being delayed or blocked, seemingly out of the blue. It’s a common scenario that many senders encounter, and it often boils down to how mailbox providers interpret your sending patterns and maintain sender reputation.
Salesforce Marketing Cloud (SFMC), provide a _Bounce Data View that allows you to extract full, unredacted bounce messages. This level of detail helps pinpoint whether the issue is a temporary rate limit (like the 4.7.28) or something else entirely.
