Email Attachments vs File-Sharing Tools: Where the 25MB Limit Comes From
It's one of the most familiar limits in computing, and also one of the least explained: try to attach a large file to an email, and somewhere around 25MB, it just refuses. Here's where that number actually comes from.
Email wasn't built to carry files
Email's underlying format was designed to carry text. An attachment gets encoded into that text-based format before it can travel with the message, which inflates its effective size by roughly a third — and the whole message, text and inflated attachment together, has to fit through every mail server that relays it along the way, not just the sender's and recipient's.
Why the limit is a hard rule, not a soft suggestion
Each mail provider sets its own cap, and the industry has settled, largely independently, around the same 20-25MB range — because every provider is on the hook for storing and relaying every message in every recipient's inbox, potentially for years. It's the same storage-cost logic that drives free file-sharing size caps, just applied to email infrastructure.
The cloud-link workaround
This is exactly why most email providers now quietly convert a large attachment into a cloud-storage link instead of actually attaching it. It sidesteps the MIME size problem — but it reintroduces the same file-sits-on-a-server-until-downloaded model that drives size limits everywhere else.
A direct transfer sidesteps the whole problem
A device-to-device transfer was never routed through mail servers or that text-based encoding in the first place, so there's no 25MB-shaped ceiling built into it to design around. The file streams at whatever size it actually is.
Related reading
Large Files Peer-to-Peer vs Client-Server: How File Sharing Actually Moves Your Data Why Free File-Sharing Tools Keep Shrinking Their Size Limits Messaging Apps vs Dedicated File Transfer Tools for Sending Documents