Developer-first Email Attachment Storage

Transactional email providers were never built to be a file store. SES drops the raw MIME after delivery, SendGrid's Inbound Parse hands you the attachment once in a multipart webhook and then forgets it, and Postmark, Mailgun, and Resend behave the same way: the bytes exist for the duration of one HTTP callback and then they are gone. If a customer later asks for the PDF they emailed your support inbox, or your finance team needs the receipt a vendor mailed three months ago, there is nothing to retrieve. files.link gives those attachments a permanent home the moment they arrive.

The integration is a thin shim inside the webhook you already run. When SendGrid Inbound Parse, Mailgun routes, or a Gmail/Microsoft Graph push notification fires, you already have the attachment buffer in memory. Pipe it straight into the three-call upload: POST /v1/files/{folderId} with your raw API key in the Authorization header returns { success, urls:[{ url, id }] }; PUT the buffer to that presigned url; then POST /v1/files/confirm-upload with { ids:[id] }.

Store the returned permanent link next to the email's message-id in your database and you have a durable, deduplicated archive keyed by thread. Outbound is the mirror image: instead of stuffing a 9 MB invoice into the message body and tripping spam filters and the 25 MB Gmail ceiling, upload it first and drop a clean link in the email — deliverability improves and the recipient downloads from a global CDN instead of pulling a base64 blob through their mail client.

Organize by sender, customer, or ISO-week using folders so audits and GDPR data-subject requests become a single folder fetch rather than a mailbox grep. Sensitive attachments — signed agreements, ID scans — go to private files served only through short-lived signed URLs your backend mints per download, never a guessable public path. Everything is encrypted at rest and moves over TLS.

Because the links never expire, you run this migration once and your email plumbing stops being the system of record for files.