What does 'rate limit exceeded' mean in email sending and should I worry?

Summary

The 'rate limit exceeded' error in email sending signifies that the sending IP or domain has surpassed the permitted sending volume within a given timeframe, as dictated by the receiving mail server or ESP. This error arises due to sending too many emails too quickly, exceeding connection limits, or triggering spam prevention mechanisms. Its a safeguard used by ESP's to protect IP reputation, and guarantee the quality of service. Whether to be concerned depends on the frequency and severity. Occasional occurrences may be temporary spikes, while frequent issues suggest problems with sending infrastructure, reputation, list hygiene, or sending practices, potentially leading to deliverability problems, service disruption, or account restrictions. Adjusting sending strategy, warming up IPs, and reviewing ESP limits are crucial steps to take.

Key findings

  • Sending Volume Threshold: Sending IP or domain exceeded the permitted sending volume in a given timeframe.
  • Spam Prevention Measure: A mechanism implemented by ESPs to prevent spam and abuse.
  • IP Reputation Protection: Rate limits serve to protect the IP reputation and ensure deliverability.
  • Recipient Overload: Rate limits may trigger when individual recipients are overwhelmed.
  • Consequences of Exceeding: Leads to service disruption, account restrictions, or suspension of privileges.
  • Inaccurate Reporting: GPT tool may show errors reported as 0% when they are actually just rounded down.

Key considerations

  • Review Sending Limits: Be aware of and adhere to sending limits imposed by your ESP.
  • Adjust Sending Strategy: Modify sending practices to stay within permissible rate limits.
  • Request Limit Increase: Consider requesting an increase to sending limits if needed.
  • Monitor Sending Patterns: Regularly monitor sending patterns to identify potential problems.
  • Ensure List Hygiene: Maintain a clean and updated email list to reduce spam and abuse complaints.
  • Implement Throttling: Consider implementing email queuing and throttling mechanisms.
  • Review Configuration: Check SES configurations including rDNS, EHLO/HELO values, sending speed, connections etc.
  • Warm up IPs: Consider warming up IP addresses especially when using new IPs.

What email marketers say
10Marketer opinions

The 'rate limit exceeded' error in email sending generally means you are sending too many emails too quickly, or exceeding the allowed sending rate or connection limits set by the email service provider (ESP). This is a safeguard to protect IP reputation, prevent spam, and maintain service quality. Whether to worry depends on the frequency of the error and its impact on your email delivery. If it's a one-time occurrence, it might be a temporary spike. However, frequent occurrences indicate underlying problems with sending infrastructure, reputation, list hygiene, or sending practices.

Key opinions

  • Sending Volume: You are sending too many emails in a short period.
  • Spam Prevention: Rate limits are in place to prevent spam and maintain service quality.
  • IP Reputation: ESPs use rate limits to protect their IP reputation and ensure deliverability for all users.
  • Delivery Impact: Frequent rate limit issues can negatively impact your email deliverability and sender reputation.
  • Individual Recipient Overload: Rate limits can be triggered by overwhelming individual recipients with emails.
  • Reason for 0% error: When errors reported are 0%, they may just be getting rounded down.

Key considerations

  • Sending Speed: Adjust your sending speed or implement throttling to avoid overwhelming the mail server.
  • List Hygiene: Ensure your email list is clean and up-to-date to reduce bounce rates and spam complaints.
  • IP Warm-up: Warm up your IP address gradually to establish a good sending reputation, especially if you're using a new IP.
  • Throttling and Queuing: Implement email queuing and throttling mechanisms to manage sending rates effectively.
  • Optimize Emails: Optimize email content and sending practices to avoid being flagged as spam.
  • Monitor Sending Reputation: Monitor your sender reputation regularly to identify and address any potential issues.
  • Examine ESP Limits: Determine if you have exceeded any ESP limits.
Marketer view

Email marketer from EmailOctopus Blog explains that rate limits are safeguards ESPs put in place to protect IP reputation. If you hit rate limits, you'll want to consider warming your IP address, consider sending less emails, or request a higher sending limit if the need arises.

December 2024 - EmailOctopus Blog
Marketer view

Marketer from Email Geeks shares that a single domain can see multiple different delivery errors in GPT and errors being reported as 0.0% are probably just being rounded down. It's likely that an error rate < 0.05% will get reported as 0.0. States rate limit exceeded might be due to individual recipients being overwhelmed with email. SES will have reasonable limits in place preventing sending unreasonable amounts of mail.

October 2024 - Email Geeks
Marketer view

Email marketer from DigitalOcean Community responds that it usually means you're exceeding the number of emails or connections allowed per unit of time. Worry if it disrupts your mail flow; otherwise, consider adjusting your sending practices.

June 2021 - DigitalOcean Community
Marketer view

Email marketer from Reddit shares that 'rate limit exceeded' typically means you're sending too many emails in a short period. Whether you should worry depends on if it's a recurring issue and impacts your sending reputation.

May 2024 - Reddit
Marketer view

Email marketer from Elastic Email explains that understanding and managing email sending limits is crucial for deliverability and preventing service disruptions. They also explain that adjusting sending speeds or the number of connections can mitigate these issues.

August 2024 - Elastic Email
Marketer view

Email marketer from Quora responds that it indicates you've hit a threshold set by the email provider to prevent spam. Worry if you see this frequently, as it could indicate deliverability issues.

August 2024 - Quora
Marketer view

Email marketer from Mailjet responds that rate limiting prevents overloading servers and helps maintain service quality, so receiving the error means you need to slow your sending or optimize your strategy.

June 2024 - Mailjet
Marketer view

Email marketer from SendPulse shares that exceeding the rate limit is a common error with email marketing. You can usually fix this issue by slowing your sends, ensuring you are warmed up, or optimizing your emails.

March 2021 - SendPulse
Marketer view

Marketer from Email Geeks explains that Google may have blocked the sender for sending too much email too quickly and for suspected spam.

February 2024 - Email Geeks
Marketer view

Email marketer from Stack Overflow explains that the error message often occurs when your application or server attempts to send too many emails through an SMTP server within a short period. You should implement queuing or throttling to manage sending rates to prevent overwhelming the mail server.

April 2023 - Stack Overflow

What the experts say
4Expert opinions

The 'rate limit exceeded' error in email sending indicates that the sending IP or domain has surpassed the allowed sending volume within a specific timeframe, as determined by the receiving mail server or ESP. The need for concern depends on the frequency and seriousness of the occurrences. Occasional incidents could stem from temporary surges, but frequent problems suggest issues with sending infrastructure, sender reputation, list hygiene, and the need to review SES configurations.

Key opinions

  • Sending Volume Threshold: The sending IP or domain exceeded the permitted sending volume within a given timeframe.
  • Recipient MX Rejection: Recipient MX server may have rejected a large volume of emails sent too quickly.
  • Sender Reputation Impact: While a one-off mistake may not significantly affect deliverability, repeated issues impact sender reputation over time.
  • Infrastructure Issues: Frequent occurrences suggest problems with sending infrastructure.
  • Sending Cleanliness: Mailstream may not be as clean as the recipient ISP requires.

Key considerations

  • Sending Infrastructure: Review and optimize sending infrastructure.
  • Sender Reputation: Monitor sender reputation for potential issues.
  • List Hygiene: Maintain good list hygiene practices.
  • Configuration Review: Check SES configuration, including rDNS, EHLO/HELO values, sending speed, and number of connections.
  • Monitor Subsequent Sends: Monitor subsequent sends, especially after IP sharing.
  • Frequency and Severity: Assess the frequency and severity of the rate limiting; occasional issues might be less critical than persistent ones.
Expert view

Expert from Email Geeks states that while a one-off mistake like this won’t likely affect deliverability too much, it will affect reputation which is measured over time. Suggests checking SES configuration, rDNS, EHLO/HELO values, sending speed, and number of connections.

February 2025 - Email Geeks
Expert view

Expert from Email Geeks suggests to monitor the next send after SES IPs are shared. If throttling happens again, then look into it.

June 2023 - Email Geeks
Expert view

Expert from Email Geeks shares that exceeding a delivery rate throttle may mean the mailstream isn't as clean as the recipient ISP wants it to be. It could also simply be that the recipient MX server rejected a large volume of emails sent too quickly.

January 2025 - Email Geeks
Expert view

Expert from Word to the Wise explains that 'rate limit exceeded' often indicates that the sending IP or domain has exceeded the permitted sending volume within a given timeframe, as defined by the receiving mail server or ESP. Whether to worry depends on the frequency and severity; occasional occurrences might be due to temporary spikes, but frequent issues suggest problems with sending infrastructure, reputation, or list hygiene that could negatively impact deliverability.

May 2022 - Word to the Wise

What the documentation says
4Technical articles

The documentation from various email service providers (AWS, Google Workspace, Twilio SendGrid, and Microsoft) consistently explains that 'rate limit exceeded' means you've surpassed the allowed sending rate or the maximum number of emails you can send per second/period. It's a mechanism to prevent abuse, ensure service quality, and maintain system health. Whether to worry depends on the context: consistent breaches may require adjusting your sending strategy or requesting higher limits, while ignoring the issue can lead to service disruption or account restrictions.

Key findings

  • Maximum Sending Rate: 'Rate limit exceeded' signifies surpassing the maximum allowed sending rate or number of emails per second/period.
  • Abuse Prevention: Rate limiting serves as a mechanism to prevent abuse and spamming.
  • Service Quality: Rate limiting helps guarantee the quality of service for all users.
  • System Health: Rate limiting assists in maintaining the overall health and stability of the email system.
  • Potential Consequences: Exceeding rate limits can result in temporary or permanent suspension of sending privileges, service disruption, or account restrictions.

Key considerations

  • Review Sending Limits: Familiarize yourself with the specific sending limits imposed by your email service provider.
  • Adjust Sending Strategy: Adapt your sending practices to remain within the permissible rate limits.
  • Request Limit Increase: If necessary, request an increase in your sending limits from your provider.
  • Monitor Sending Patterns: Regularly monitor your sending patterns to identify and address any potential issues.
  • Understand Implications: Understand the potential implications of exceeding rate limits on your account and service.
Technical article

Documentation from Google Workspace Admin Help indicates exceeding sending limits (which can lead to rate limiting) should be addressed by reviewing the sending limits. Admins should understand these limits to avoid service disruption and potential account restrictions.

December 2022 - Google Workspace Admin Help
Technical article

Documentation from Twilio SendGrid explains that rate limiting is a method used to prevent abuse and guarantee the quality of service. Exceeding rate limits can lead to temporary or permanent suspension of sending privileges.

April 2024 - Twilio SendGrid
Technical article

Documentation from Microsoft explains that Exchange Online has sending limits to prevent spam and maintain system health. Encountering 'rate limit exceeded' should prompt a review of sending patterns and potential adjustments.

April 2024 - Microsoft
Technical article

Documentation from Amazon AWS explains that 'Rate limit exceeded' means you've exceeded the maximum sending rate or maximum number of emails you can send per second. Worrying depends on the context. If you're consistently hitting the limit, you may need to request an increase or adjust your sending strategy.

September 2023 - Amazon AWS