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When an inbound email includes attachments, openmail stores them and provides signed download URLs.

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How it works

  1. Email arrives with attachments
  2. We upload each file to secure storage
  3. Attachment metadata (filename, content type, size, download URL) is included in the webhook payload and message responses

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Downloading attachments

Each attachment includes a url field in the message response: 
https://api.openmail.sh/v1/attachments/{messageId}/{filename}
This endpoint requires authentication and returns a 302 redirect to a signed URL that expires in 15 minutes. 
curl -L https://api.openmail.sh/v1/attachments/msg_4c8d5e6f/receipt.pdf \
  -H "Authorization: Bearer om_live_..."

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Limits

  • Maximum attachment size is determined by the email provider (typically 25MB per email)
  • Attachment URLs in webhook payloads should be fetched promptly; signed URLs expire