Proton Mail Attachment Guide (2026)
Proton Mail 25MB Attachment Limit Guide
Proton Mail provides end-to-end encrypted email, but message attachments are capped at 25 MB (≈19 MB practical after MIME encoding).
File too large for Proton Mail?
Send up to 3 GB free with zero-knowledge browser encryption · No accounts, auto-purged links
Send file via LimeShare linkProton Mail limit breakdown
| Constraint | Details |
|---|---|
| Stated attachment limit | 25 MB per message |
| Encoding overhead | 33% Base64 expansion |
| Cloud fallback behavior | Requires Proton Drive account |
| Recipient requirement | Any recipient |
| Privacy & scanning | PGP encrypted at rest |
Why files bounce on Proton Mail
Encrypted PGP emails still travel over standard SMTP protocols, subject to the universal 25 MB gateway limit.
How to send files larger than 25 MB
- Encrypt files up to 3 GB with LimeShare in your browser.
- Paste the resulting link into your Proton Mail draft.
- Add an Argon2id password and share it via encrypted Proton Mail or Signal.
Frequently asked questions
How can I send a 2 GB file via Proton Mail?
Use LimeShare to generate an encrypted self-destructing link and paste it into your Proton Mail message.