This error occurs when the SMTP username and password provided to connect to the SMTP endpoint of Amazon SES are incorrect.
1. Verify credentials
Ensure that the username and password you enter are correct and the same one SES provided.
2. Verify the region
SMTP credentials in Amazon SES differ per region. Therefore, ensure that the credentials used are associated with your region.
3. Use SMTP credentials and not console credentials
It is important to note that the credentials used in the SMTP endpoint are not the same as those you use for AWS. It would help if you had the Amazon SES SMTP credentials to access the Amazon SES SMTP interface.
You will have to create an IAM user that can invoke the SES services and generate SMTP credentials for the newly created IAM user. It can be done using the SES console.
First, navigate to your SES account dashboard. You will see a section titled - "SMTP Settings." Under this, you should see the output shown below.
Figure - Viewing SES Settings in AWS Console
Click "Create SMTP Credentials." This will direct you to the IAM Console, where you will be prompted to create an IAM User with the policies required to invoke SES.
Figure - Creating the IAM user
Afterward, click "Create." This will create the IAM User, generate the credentials, and display the output below.
Figure - Viewing the SMTP credentials for IAM user
To resolve the error, you can download the generated credentials and provide these values for the SMTP username/password.
View all errors