Problem
Emails could not be sent through Amazon Simple Email Service (Amazon SES) due to a "SMTPDataError."
Explanation
- This error occurs when the Simple Mail Transfer Protocol (SMTP) connection is not correctly established for sending emails.
- Amazon SES imposes sending limits to control the number of emails that can be sent within 24 hours (daily sending quota) and per second.
- Suppose the number of messages exceeds the daily maximum for your AWS account. In that case, the API call made from MoEngage to Amazon SES will be rejected, resulting in a "454 Throttling failures: Daily message quota exceeded error(SMPTDataError)".
Solution
To avoid this error during bulk email sending, consider the following points in coordination with the customer or Amazon support team:
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IP usage
Verify if the customer uses Amazon's dedicated or shared IPs.- Dedicated IP. The request limit is 40 emails per second for each IP. For example, if the customer uses three dedicated IPs, the limit would be 120 emails per second.
- Shared IPs. The request limit is 500 emails per second, but the domain reputation might decline if multiple Amazon customers use the same IP.
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Throttling settings
Adjust throttling at the global level and campaign-level delivery control. For example, to target 55L users in a one-time Email campaign, it is recommended to use ten dedicated or shared IPs and set throttling to 20000 emails per minute in global and campaign settings. -
Daily email request limit
Confirm the total email request limit per day in the customer's Amazon account.
For more information, refer to:
- Errors related to the sending quotas for your Amazon Simple Email Service (SES).
- What is Amazon SES?