Secure File Sharing Between Devices: Beyond Email Attachments

Most file sharing happens via email attachments, which has substantial security limitations. Modern alternatives provide better security, better recipient experience, and better handling of large files. Understanding the options helps you pick the right method for each situation.

Why Email Attachments Are Problematic

**Not encrypted end-to-end.** Email providers can read attachments. If you email yourself, attachments go through mail servers readable by providers.

**Size limitations.** Gmail limits to 25MB. Attachments larger than this fail or require workarounds.

**Permanent in email.** Attachments remain in the recipient's email indefinitely, often syncing to multiple devices and backups.

**Phishing attack vector.** Email attachments are a primary malware delivery method. Recipients may be hesitant to open attachments from unexpected senders.

**Lost tracking.** Who downloaded, when, how many times — no visibility.

Options for Sharing with Yourself (Your Own Devices)

**iCloud, Google Drive, OneDrive, Dropbox.** Sync files automatically between your devices. Reasonable security for most purposes. Not end-to-end encrypted by default, meaning cloud provider can access files.

**Apple AirDrop.** Local wireless file transfer between Apple devices. Fast, private (not through cloud), no size limits. Only works between Apple devices.

**Quick Share (Google).** Android equivalent of AirDrop. Local wireless transfer between Android devices.

**LocalSend.** Open-source cross-platform (Windows, Mac, Linux, Android, iOS) local wireless file sharing. Works like AirDrop between any devices on the same network.

**USB thumb drive.** Low-tech but reliable. No internet dependency. Hardware encrypted drives provide good security.

Options for Sharing with Others

**Encrypted file sharing services:**

**Firefox Send alternative:** Firefox Send was shut down. The modern equivalent is Send by Mozilla or alternatives like OnionShare for anonymous sharing.

**Signal messenger.** Encrypted file sharing up to 100MB. Good for sharing with Signal contacts.

**Tresorit.** Encrypted file sharing service. $12/month for individual plan. End-to-end encrypted even from Tresorit.

**ProtonDrive.** From the makers of ProtonMail. End-to-end encrypted file sharing. Free tier available.

**Cloud shares (Google Drive, OneDrive, Dropbox):** easier than specialized services but not end-to-end encrypted. Fine for non-sensitive sharing.

For Large Files

Email attachment limits make large file sharing impractical. Options:

**Cloud storage share link.** Upload to Google Drive/Dropbox/OneDrive, share link. Easiest for most purposes. Add password protection where available.

**WeTransfer.** Free up to 2GB, pro service for larger. Easy but files hosted on WeTransfer.

**Hightail.** Business-focused large file sharing.

**Direct peer-to-peer.** Services like LocalSend or ToffeeShare transfer directly between browsers without uploading to intermediary. Technically interesting but less user-friendly.

For Sensitive Business Files

**Encrypted cloud sharing with password.** Attachment password-protected before upload, password shared via different channel.

**Signal or similar encrypted messenger.** Up to 100MB files.

**Encrypted email services.** ProtonMail attaches encrypted files between Proton users. Tutanota similar.

**S/MIME or PGP email encryption.** More complex but allows encryption on standard email. Rarely used in practice.

**Enterprise file sharing services.** Box, Egnyte, Citrix ShareFile for business use with compliance requirements.

Specific Scenarios

**Share vacation photos with family:** Google Photos shared album or iCloud shared album. Easy, works across platforms, no size concerns.

**Send tax documents to accountant:** cloud storage share link with password. Or accountant's dedicated secure portal if they have one.

**Collaborate on documents with team:** Google Workspace, Microsoft 365, Dropbox. Real-time collaboration more valuable than security for most teams.

**Share sensitive personal information with family:** Signal messenger. End-to-end encrypted.

**Transfer files between your laptop and phone:** AirDrop (Apple), Quick Share (Android), LocalSend (cross-platform).

**Share with someone outside your organization:** cloud share link usually easiest. For sensitive sharing, encrypted services.

Best Practices Regardless of Method

**Delete after sharing.** Most sharing services allow setting expiration dates. Use them.

**Password protect sensitive files.** 7-Zip and similar can encrypt files with passwords before sharing. Share password via different channel.

**Verify recipient received.** Confirm the file arrived and is openable. Prevents mysteries later.

**Avoid repeated sharing of the same file.** Each copy is another potential loss point. Share once, remind recipient to retrieve.

**Clean up old shares.** Review shared files periodically. Revoke access to files no longer needing to be shared.

The Practical Framework

**Between your own devices:** cloud sync (iCloud, Google, OneDrive, Dropbox) for ongoing, AirDrop/Quick Share/LocalSend for one-off transfers.

**With trusted recipients (family, close friends):** cloud share link for files, Signal for sensitive sharing.

**With less-known recipients (one-off professional sharing):** cloud share link with password, or dedicated sharing service.

**For sensitive business:** encrypted sharing service (ProtonDrive, Tresorit) or your company's dedicated secure file sharing.

The modern options are substantially better than email attachments for most sharing scenarios. The one-time setup effort of knowing which tool to use for which situation pays off across years of file sharing needs.