How to Send Large Files by Email (Without Attachment Bounce-Backs)
Email protocols were never designed for multi-gigabyte binary payloads. Learn why 18.5MB files bounce on a 25MB limit and how expiring object-storage links solve delivery.
Why email attachments fail well below the advertised limit
Most major email providers (including Gmail, Google Workspace, and Microsoft 365) enforce a 20MB to 25MB total message ceiling. Because SMTP transports 7-bit text, binary attachments are encoded using MIME Base64, which maps every 3 bytes of binary data into 4 ASCII characters plus CRLF line breaks — inflating the raw byte size by approximately 33% to 37%.
As a result, an 18.5MB PDF or ZIP file expands to roughly 25MB on the wire and can be rejected by either the sending server or the recipient's corporate mail gateway with an SMTP 552 'Message size exceeds fixed maximum message size' bounce.
Why cloud drive folders often create permission friction
Sharing a folder from a synced cloud drive frequently forces external recipients to sign in with a matching corporate account or request access permissions. Worse, files left in shared folders remain accessible indefinitely unless you remember to revoke them manually.
Point-in-time file transfer separates transient delivery from permanent drive storage: your recipient receives a single expiring link that works in any browser without registration.
Replacing inline attachments with expiring transfer links
Instead of pushing gigabytes through mail relays, modern file transfer uploads the binary directly to private object storage in parallel multipart chunks, verifies the byte size, scans for malware in quarantine, and inserts a compact, expiring HTTPS link into your email.
With Attach & Send, you can upload up to 2GB free without creating an account, set an optional password, and let your recipient download directly over HTTPS.
Try Attach & Send free
Upload up to 2 GB with password protection and 3-day link expiry — no account needed.