MinIO Filelink: send large attachments without letting them leave the company

calendar Jul 10, 2026 · 2 min read · thunderbird email minio s3 security open-source  ·
Share on: linkedin copy

We've just published MinIO Filelink, a Thunderbird extension that changes how large attachments are sent by email.

The problem

Big attachments are awkward: many mail providers cap message size, large files bloat mailboxes on both ends, and — for a company handling sensitive documents — every attachment sent is a copy of that document leaving the organization's control, often landing in a third-party inbox or file-sharing service you don't manage.

MinIO Filelink plugs into Thunderbird's native "Filelink" feature: instead of attaching the file itself, Thunderbird uploads it to a MinIO server and inserts a link in the message. The recipient clicks the link to download the file — the mailbox only ever carries a URL.

  • Your server, your rules — point it at a MinIO (or any S3-compatible) endpoint you control, private or public. The attachment never has to leave your infrastructure.
  • Links that expire — download links are presigned URLs valid for a configurable duration, not permanent public links.
  • One configuration per account — different Thunderbird accounts can use different MinIO servers and buckets.
  • Handles large files reliably — uploads above a configurable size are automatically sent as multipart.

Why it matters for security

By keeping attachments on infrastructure the company controls, with links that stop working after a set time, MinIO Filelink reduces the exposure of sensitive documents compared to sending them as permanent, uncontrolled copies through email.

MinIO Filelink is free and open source (MIT license), with the code available on GitHub.

👉 Discover MinIO Filelink or install it directly from the Thunderbird Add-ons store.

Launch the application

Translations: