[Feature Request] Email metadata to Custom Fields

Description In my workflow, i need to import email attachments while keeping the original name of the document. With the automatic date detection of documents, it's hard to map an imported document to an email. Therefore i need custom fields that reference some email metadata like the subject, recieved date, sender and reciever. I created a fork and implemented the feature: [paperless-ngx/feature-mail-metadata-custom-fields]( It automatically creates four custom fields and populates them, as soon as a mail gets imported. It works well for me and helped my worflow massively: <img width="500" alt="Bildschirmfoto 2025-08-09 um 17 43 18_anonymized" src=" /> Is this something that would be considered as a pull request and therefore worth refining for public use? There would be a few things to consider when implementing it, for example, how translations would work. On top of the custom fields, it helped my workflow a lot that the document d…