SES and Sender authorization, or custom E-mail headers?

Hey there.

I’m currently setting up GitLab on AWS, and want to use SES for notification E-mails, etc. Because of our enterprise AWS account structure, the IAM user that provides the SMTP credentials lives in a different account than the one in which the SES identity is being setup in. This in itself is no issue, as AWS allows so called “sender authorization” that grants a principal in a different account permission to use the SES identity.

This is all described here: https://aws.amazon.com/about-aws/whats-new/2015/07/amazon-ses-now-supports-cross-account-sending/

The issue I am facing now is: To make this work, I have to send additional Headers in the Data section of the E-mail, which include the ARN for the SES identity. So far I do not see any way to configure GitLab to include special E-mail headers, which is an absolute must for this to work.

Any Ideas where I could configure something like this?