[Feature]: Attachment Deduplication

[AsGamer1]

Is your feature request related to a problem?

Yes. Mail Archiver currently stores every attachment independently, even when the attachment content is identical. In my installation (~17,000 emails and ~100,000 attachments), the database size is about 22 GB. After analyzing the attachment data, I found that approximately 10.59 GB consists of duplicate attachments, mostly email signature images, logos, and other frequently repeated files.

Describe the solution you'd like

Implement attachment deduplication based on a content hash. Store each unique attachment only once and let multiple email records reference the same attachment blob. This would significantly reduce storage requirements while preserving existing functionality.

Additional context

I analyzed the PostgreSQL database and calculated:

Unique attachment data: ~9.87 GB
Duplicate attachment data: ~10.59 GB

This means that nearly 50% of the attachment storage could potentially be saved through deduplication. The largest source of duplication appears to be embedded images from email signatures and other recurring attachments.

[s1t5]

I have implemented deduplication for the attachments, which is available under the dev tag of the container. Feel free to test it out. This will also be part of the next release.

Information about the new feature can be found here.