# InvalidSignatureException when sending via SES API – Works in Postman, fails in Plugin (Mautic 5.2.6, etailors AmazonSesBundle)
**URL:** https://forum.mautic.org/t/invalidsignatureexception-when-sending-via-ses-api-works-in-postman-fails-in-plugin-mautic-5-2-6-etailors-amazonsesbundle/36185
**Category:** Mautic 5 Install/Upgrade Support
**Created:** [July 24, 2025, 5:06pm UTC](https://forum.mautic.org/t/invalidsignatureexception-when-sending-via-ses-api-works-in-postman-fails-in-plugin-mautic-5-2-6-etailors-amazonsesbundle/36185 "2025-07-24T17:06:09Z")
**Posts on this page:** 4
**Page:** 1
### Author:  [@mcgumbel](https://forum.mautic.org/u/mcgumbel)
#### Post date: [July 24, 2025, 5:06pm UTC](https://forum.mautic.org/t/invalidsignatureexception-when-sending-via-ses-api-works-in-postman-fails-in-plugin-mautic-5-2-6-etailors-amazonsesbundle/36185/1 "2025-07-24T17:06:09Z")
**Your software**
My Mautic version is: 5.2.5
My PHP version is: 8.1
My Database type and version is:
**Your problem**
Hi everyone,
I’m experiencing a problem with sending emails via the etailors\_amazon\_ses plugin (AmazonSesBundle) in Mautic.
**Sending via the SES API works perfectly with my credentials in Postman, but not through the plugin in Mautic.**
* * *
**What works:**
- Sending emails via the SES API using the same AWS IAM credentials and region (`eu-west-1`) in Postman → **works**.
- Test emails via the plugin work, but segment and campaign emails never do.
* * *
**What does not work:**
- Sending segment or campaign emails via the plugin always results in the following error:
- InvalidSignatureException (client): The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method.
- The error persists even after updating to the latest plugin version.
- Server time is synchronized (UTC), credentials and permissions are correct, region matches.
* * *
**Example log excerpt:**
AWS SES Error: Error executing “SendEmail” on “[https://email.eu-west-1.amazonaws.com/v2/email/outbound-emails](https://email.eu-west-1.amazonaws.com/v2/email/outbound-emails)”; AWS HTTP error: Client error: `POST https://email.eu-west-1.amazonaws.com/v2/email/outbound-emails` resulted in a `403 Forbidden` response: {“message”:“The request signature we calculated does not match the signature you provided. Check your AWS Secret Access Key and signing method. Consult the service documentation for details.”}
**Payload (shortened):**
{ “FromEmailAddress”: “NAME [name@example.com](mailto:name@example.com)”, “Destination”: { “ToAddresses”: [“Vorname\_Testcontact\_250515\_195649 Nachname\_Testcontact\_250515\_195649 [email\_Testcontact\_250515\_195649@example.com](mailto:email_Testcontact_250515_195649@example.com)”] }, “Content”: { “Raw”: { “Data”: “…” } } }
* * *
**What I have already checked:**
- AWS IAM user has all required permissions (`ses:SendEmail`, `ses:SendRawEmail`, `ses:GetAccount`).
- Secret key does not contain special characters.
- Region is set correctly everywhere (`eu-west-1`).
- Server time is synchronized (UTC).
- Latest version of the plugin is installed (manually updated from GitHub).
- Sending with Postman works using the same credentials and payload.
- The error also occurs with minimal email content (plain text only, no special characters, no HTML).
- domain and e-mailadress are verified with AWS
* * *
**Question/Request:**
Are there any known incompatibilities with Mautic 5.x or Symfony?
Could this be related to signature generation for multipart emails or specific headers?
Do you have any tips on how I can further debug or work around this issue?
**Thank you for your support!**
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### Author:  [@mcgumbel](https://forum.mautic.org/u/mcgumbel)
#### Post date: [July 25, 2025, 8:12am UTC](https://forum.mautic.org/t/invalidsignatureexception-when-sending-via-ses-api-works-in-postman-fails-in-plugin-mautic-5-2-6-etailors-amazonsesbundle/36185/2 "2025-07-25T08:12:34Z")
[Mautic 5.0.3 AWS SNS endpoint is not working. GIve a solution to handle bounce and Complaint emails - #51 by benbon](https://forum.mautic.org/t/mautic-5-0-3-aws-sns-endpoint-is-not-working-give-a-solution-to-handle-bounce-and-complaint-emails/31334/51) - this suggestion did also not work
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### Author:  [@mcgumbel](https://forum.mautic.org/u/mcgumbel)
#### Post date: [July 28, 2025, 11:41am UTC](https://forum.mautic.org/t/invalidsignatureexception-when-sending-via-ses-api-works-in-postman-fails-in-plugin-mautic-5-2-6-etailors-amazonsesbundle/36185/3 "2025-07-28T11:41:16Z")
I found the solution. I documented it directly at the plugins GitHub repository: [InvalidSignatureException when sending via SES API – Works in Postman, fails in Plugin (Mautic 5.2.6) · Issue #73 · pm-pmaas/etailors\_amazon\_ses · GitHub](https://github.com/pm-pmaas/etailors_amazon_ses/issues/73)
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### Author:  [@system](https://forum.mautic.org/u/system)
#### Post date: [July 29, 2025, 11:41pm UTC](https://forum.mautic.org/t/invalidsignatureexception-when-sending-via-ses-api-works-in-postman-fails-in-plugin-mautic-5-2-6-etailors-amazonsesbundle/36185/4 "2025-07-29T23:41:47Z")
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