Why are some emails not being delivered through Amazon SES?

Summary

Email deliverability issues with Amazon SES can arise from numerous factors relating to authentication, reputation, content, list management, sending practices, and technical configurations. Authentication problems with SPF, DKIM, and DMARC can lead to emails being flagged as spam. Poor IP reputation, due to shared IPs, lack of IP warming, or sudden volume increases, negatively impacts deliverability. Problematic content, such as spam trigger words or links to websites with poor reputations, also contributes to deliverability issues. Furthermore, sending to invalid addresses, unengaged subscribers, or failing to honor unsubscribe requests harms sender reputation. Technical configurations, such as missing or misconfigured rDNS records, and exceeding sending limits, can also cause problems. Amazon SES's global suppression list can block emails to addresses that have previously bounced or complained. Finally, temporary issues, such as problems with the receiving server, may also be responsible.

Key findings

  • Authentication: Incorrect or missing SPF, DKIM, and DMARC records can cause emails to be marked as spam.
  • IP Reputation: Poor IP reputation from shared IPs, lack of warming, or sudden volume spikes harms deliverability.
  • Content: Spam trigger words and links to low-reputation sites can lead to spam flagging.
  • List Management: Sending to invalid addresses, unengaged subscribers, and failing to honor unsubscribes damages sender reputation.
  • Technical Configurations: Missing or misconfigured rDNS records and exceeding sending limits can cause delivery failures.
  • Suppression List: Amazon SES's global suppression list blocks emails to addresses with prior bounces or complaints.
  • Temporary Issues: Problems with the receiving server can temporarily block email delivery.

Key considerations

  • Authentication Setup: Properly configure SPF, DKIM, and DMARC for your sending domain.
  • IP Warming: Gradually warm up your IP address when starting with a new provider or increasing volume.
  • Content Review: Avoid spam trigger words and check the reputation of linked websites.
  • List Hygiene: Regularly clean your email list to remove invalid or unengaged addresses.
  • Unsubscribe Handling: Ensure timely processing of unsubscribe requests.
  • Technical Configuration: Configure rDNS records correctly and stay within sending limits.
  • Suppression Management: Monitor and manage bounces and complaints, and be aware of the Amazon SES suppression list.
  • Monitoring: Regularly monitor sender reputation, bounce rates, and complaint rates to proactively identify and address issues.
  • Troubleshooting: Be prepared to troubleshoot temporary technical issues on the recipient's side.

What email marketers say
11Marketer opinions

Several factors can contribute to email deliverability issues when using Amazon SES. These include authentication problems (SPF, DKIM, DMARC), poor IP reputation (due to shared IPs or lack of IP warming), spam trigger words in email content, URLs to websites with bad reputations, sending to unengaged subscribers, abrupt increases in sending volume, exceeding sending limits, not honoring unsubscribe requests, and failing to set up feedback loops. Checking reputation, bounce rates, complaint rates, and suppressions are also essential.

Key opinions

  • Authentication: Incorrect or missing SPF, DKIM, and DMARC records can lead to emails being flagged as spam.
  • IP Reputation: A poor IP reputation, whether due to shared IPs or inadequate IP warming, can negatively impact deliverability.
  • Content: Using spam trigger words or including URLs to websites with poor reputations can cause emails to be marked as spam.
  • List Health: Sending emails to unengaged subscribers can harm sender reputation and deliverability.
  • Sending Volume: Abruptly increasing sending volume or exceeding sending limits can trigger spam filters.
  • Unsubscribes: Not honoring unsubscribe requests promptly can lead to spam complaints.
  • Feedback Loops: Lack of feedback loops prevents you from receiving information about spam complaints.

Key considerations

  • Authentication Setup: Ensure SPF, DKIM, and DMARC are properly configured for your sending domain.
  • IP Warm-up: Gradually warm up your IP address when starting with a new provider or increasing sending volume.
  • Content Review: Avoid spam trigger words and check the reputation of URLs included in your emails.
  • List Segmentation: Segment your email list and focus on sending to engaged subscribers.
  • Sending Limits: Monitor your sending limits and adjust volume accordingly.
  • Unsubscribe Handling: Ensure your system processes unsubscribe requests immediately.
  • Feedback Loops: Set up feedback loops with major ISPs to receive spam complaint data.
  • Monitor Reputation: Regularly monitor your sender reputation, bounce rates, and complaint rates in Amazon SES.
  • Suppression List: Be aware of the Amazon SES suppression list and remove suppressed addresses from your sending list.
Marketer view

Email marketer from Gmass explains that exceeding the sending limits imposed by Amazon SES can lead to deliverability problems. Monitor your sending limits and adjust your sending volume accordingly.

February 2024 - Gmass
Marketer view

Marketer from Email Geeks asks about the custom return-path and DKIM signing and if the SES reputation dashboard is showing any issues with bounces and complaints.

October 2021 - Email Geeks
Marketer view

Email marketer from Reddit shares that using spam trigger words in your email content can cause deliverability issues with Amazon SES. Phrases like 'free,' 'guarantee,' and excessive use of exclamation marks can flag your emails as spam.

May 2021 - Reddit
Marketer view

Email marketer from MailerQ explains that not setting up feedback loops (FBLs) with major ISPs can prevent you from receiving information about spam complaints, making it difficult to improve your deliverability with Amazon SES. FBLs provide valuable data for identifying and addressing deliverability issues.

March 2023 - MailerQ
Marketer view

Email marketer from Litmus explains that abruptly increasing your sending volume can trigger spam filters and cause deliverability issues with Amazon SES. It's crucial to warm up your IP address gradually when starting to send emails through a new provider.

May 2021 - Litmus
Marketer view

Email marketer from Mailjet Blog explains that a poor IP reputation can lead to deliverability problems with Amazon SES. Shared IPs used by other senders can negatively affect your email delivery. The blog suggests warming up your IP address gradually to build a positive reputation.

June 2021 - Mailjet Blog
Marketer view

Email marketer from SparkPost explains that not honoring unsubscribe requests promptly can lead to recipients marking your emails as spam and negatively impact your deliverability with Amazon SES. Ensure that your system processes unsubscribe requests immediately.

March 2025 - SparkPost
Marketer view

Email marketer from StackOverflow explains that including URLs to websites that have a bad reputation will often result in emails being flagged as SPAM. You must check your URL reputation.

August 2024 - StackOverflow
Marketer view

Email marketer from SendGrid Blog shares that not properly authenticating your emails with SPF, DKIM, and DMARC can cause deliverability issues. Incorrectly configured DNS records, or missing authentication altogether, can lead inbox providers to flag your emails as spam.

July 2023 - SendGrid Blog
Marketer view

Email marketer from Email on Acid explains that sending emails to unengaged subscribers can harm your sender reputation and deliverability with Amazon SES. It recommends regularly segmenting your email list and focusing on engaged recipients.

November 2021 - Email on Acid
Marketer view

Marketer from Email Geeks asks about the volume of messages being sent, how many are not reaching recipients, if there is a pattern with the not-reached addresses, and what is connected to SES to manage the send.

August 2024 - Email Geeks

What the experts say
3Expert opinions

Email delivery issues with Amazon SES can stem from several factors. Amazon SES maintains a global suppression list of email addresses that have previously bounced or complained; if an address is on this list, delivery will fail regardless of sender reputation. Additionally, a sudden spike in email volume from a new SES account can trigger spam filters and harm deliverability, making IP warming crucial. Finally, temporary issues like the recipient server's technical difficulties or DNS problems can also prevent email delivery.

Key opinions

  • Suppression List: Amazon SES's global suppression list blocks emails to addresses that previously bounced or complained.
  • Volume Spike: A sudden increase in email volume from a new SES account can trigger spam filters.
  • Temporary Issues: Recipient server technical difficulties or DNS problems can prevent email delivery.

Key considerations

  • Suppression Management: Regularly check and manage your recipient lists against suppression lists to avoid sending to problematic addresses.
  • IP Warming: Gradually increase email volume when starting with a new SES account to establish a positive sending reputation.
  • Troubleshooting: Be aware that temporary issues on the recipient's end can impact delivery, and troubleshooting may require patience and communication with the recipient.
Expert view

Expert from Word to the Wise explains that temporary issues can arise due to the receiving server experiencing technical difficulties. A DNS issue at the recipients end can affect if they get the email, or a technical issue between hops along the way can occur.

January 2025 - Word to the Wise
Expert view

Expert from Spam Resource explains that Amazon SES has a global suppression list which includes email addresses that have previously bounced or complained. If a recipient is on this list, your emails will not be delivered, regardless of your sender reputation. This can occur because of a previous sender marking the email as spam.

June 2022 - Spam Resource
Expert view

Expert from Spam Resource explains that a sudden increase in email volume from a new Amazon SES account can trigger spam filters and negatively impact deliverability. It is best to warm up your IP address.

June 2022 - Spam Resource

What the documentation says
4Technical articles

Email deliverability issues with Amazon SES can stem from sending emails to invalid addresses, resulting in bounces. High bounce and complaint rates negatively impact sender reputation. A missing or misconfigured reverse DNS (rDNS) record can also cause deliverability problems, as some email providers use rDNS to verify sending server legitimacy.

Key findings

  • Invalid Addresses: Sending to invalid email addresses leads to bounces and damages sender reputation.
  • Bounce Rate: High bounce rates negatively impact sender reputation and deliverability.
  • Complaint Rate: High complaint rates severely damage sender reputation and result in deliverability problems.
  • Reverse DNS: Missing or misconfigured reverse DNS (rDNS) records can cause deliverability issues.

Key considerations

  • List Hygiene: Regularly clean your email list to remove invalid addresses.
  • Bounce Handling: Promptly remove hard bounces from your sending list.
  • Content Relevance: Send relevant content and provide easy unsubscribe options to minimize complaints.
  • Reverse DNS Setup: Configure a reverse DNS (rDNS) record for your sending IP address and ensure it matches your domain name.
Technical article

Documentation from Amazon Web Services explains that high bounce rates can negatively impact your sender reputation, leading to deliverability issues. Hard bounces, in particular, should be addressed promptly by removing the invalid email addresses from your sending list. Amazon SES provides mechanisms for automatically handling bounces, such as using Amazon Simple Notification Service (SNS) to receive bounce notifications.

May 2023 - Amazon Web Services
Technical article

Documentation from DigitalOcean explains that not having a reverse DNS (rDNS) record set up for your sending IP address can cause deliverability issues. Some email providers use rDNS to verify the legitimacy of the sending server. The reverse DNS must also match the domain name used in your email.

September 2021 - DigitalOcean
Technical article

Documentation from Amazon Web Services explains that high complaint rates (when recipients mark your emails as spam) can severely damage your sender reputation and result in deliverability problems. It emphasizes the importance of sending relevant and desired content to recipients and providing an easy way for them to unsubscribe from your emails. Amazon SES also provides mechanisms for handling complaints, such as using Amazon SNS to receive complaint notifications.

May 2023 - Amazon Web Services
Technical article

Documentation from Amazon Web Services explains that deliverability issues can arise from sending emails to invalid email addresses. It recommends regularly cleaning your email list to remove invalid addresses, as sending to these addresses can negatively impact your sender reputation and lead to deliverability problems.

September 2022 - Amazon Web Services