kmdpartners / aws-lambda-attachment-extractor

Simple event driven AWS Lambda Python function to extract a ZIP or GZIP attachment from an email stored in S3 by another service (such as Amazon SES).

AWS Lambda Attachment Extractor

This is a very simple project which can be used for reference when creating Lambda functions to manipulate email files stored to an Amazon S3 bucket, typically by an inbound SES routing rule. See 'AWS Documentation' for more information.

Use cases

The original use for this project was to process DMARC reports, getting .ZIP and .GZIP attachments from emails stored in S3 and extracting the archives, resulting in .XML files, which are then uploaded to another S3 bucket for processing by another service.

The Python file doesn't perform security checks on attachments and will ignore anything which does not result in an .XML file. The original email is not deleted after processing takes place, however, this functionality could be added. Alternatively a S3 bucket transition policy can be used.

This type of processing may be very useful for extracting DMARC reports, which are sent by email service providers to an email address specified in the rua section of your DMARC DNS record, see https://dmarc.org/overview/. You will then be left with a bucket of XML DMARC reports which you may wish to process manually or upload to a service such as https://dmarcian.com/dmarc-xml/.

Getting Started

To get started, simply upload the python file to Lambda, changing the variables if required. This lambda function expects a S3 put event to trigger it, see 'this tutorial' for more information.