Amazon SES: Message Sending Failed – The Following SMTP Error was Encountered: 552 5.3.4 Message is Too Long

In email communication, encountering errors can be frustrating and disruptive. One such error you may encounter while using Amazon Simple Email Service (SES) is the dreaded “552 5.3.4 Message is too long” SMTP error. This error occurs when the message you are trying to send exceeds the message length limit imposed by Amazon SES, which is set at 10 MB and cannot be increased.

Understanding the Error

When you attempt to send an email using Amazon SES, it is crucial to be mindful of the message size. The 552 5.3.4 error indicates that the message you are trying to send is larger than the allowed limit. This limit includes both the content of your email and any attachments you may have formed.

Factors Contributing to the Error

Two main factors can contribute to the occurrence of this error. The first factor is the overall size of your email’s content, including images, text, and other multimedia elements. The second factor is the base64 encoding of your message. Base64 encoding ensures that non-textual data, such as images or attachments, can be transmitted via email. However, the encoded version of your message can sometimes exceed the size limit, triggering the error.

Resolving the Issue

To overcome this error and successfully send your email through Amazon SES, there are a few solutions you can consider:

1. Shorten Your Message Length: The most straightforward solution is to reduce the overall size of your email. This can be achieved by removing unnecessary content, compressing images, or optimizing multimedia elements. Keeping your message concise and to the point ensures it falls within the allowable limit.

2. Utilize External Services: If you frequently need to send large amounts of text or files, consider leveraging external services such as Google Drive or Dropbox. These platforms allow you to upload and share your content via a link in your email instead. By doing so, you can bypass the size limitations imposed by Amazon SES and ensure your recipients can access the complete message.


Encountering the “552 5.3.4 Message is too long” SMTP error while using Amazon SES can be a setback, but it can be resolved efficiently with the right approach. By understanding the factors contributing to this error and implementing the suggested solutions, you can ensure your emails are delivered successfully without compromising the content you wish to share.

Remember, keeping your messages concise and utilizing external services when necessary can help you navigate the limitations imposed by Amazon SES. By doing so, you can continue communicating effectively and efficiently through email, ensuring your messages reach their intended recipients without hiccups.