The ‘Signature does not match’ error usually occurs when you’re configuring the Amazon SES mailer and the Secret Access Key in your SMTP plugin is incorrect. This might be due to the key being expired or containing special characters.
Resolving the Error – Solution
We’ll show you how to fix this using WP Mail SMTP as an example.
To resolve this error, we recommend recreating your access key from AWS. To do this, log into your AWS account, navigate to the Users page, and select the Security credentials tab. From there, click on the Create access key button.
Once you have the Access key and the Secret access key, be sure to paste them in the WP Mail SMTP’s plugin settings.
For more information and a detailed guide, refer to WP Mail SMTP’s guide on Amazon SES mailer.