Send PDF safely by email — what you need to know about security

2 min read·25 July 2026

Email is not always secure. If you send sensitive documents as PDFs — contracts, pay slips, medical records — there are risks. This guide covers how to send a PDF safely by email and what extra measures you can take.

Risks of sending PDFs by email

Standard email is not end-to-end encrypted. This means an attachment is theoretically readable by intermediaries (mail servers, providers) if the email traffic is not encrypted. Extra protection is recommended for sensitive documents.

Add a password to the PDF

The simplest extra protection: add a password to the PDF via PDFrust Protect before sending. Always send the password via a separate channel — SMS, phone or another app. Never put the password in the same email as the PDF.

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File size and email limits

Most email providers have an attachment limit of 10–25 MB. Gmail: 25 MB, Outlook: 20 MB, iCloud Mail: 20 MB. Exceeding the limit? Compress the PDF first via PDFrust Compress, or share via a cloud link (Google Drive, Dropbox, WeTransfer).

Encrypted email: when is it needed?

For highly sensitive documents (medical records, legal documents, banking matters) consider encrypted email: ProtonMail, Tutanota or S/MIME in Outlook/Apple Mail. This encrypts the attachment end-to-end so only the recipient can read it.

Alternative: secure file sharing

Instead of an email attachment: share via a secure link with password protection and expiry date. Services like WeTransfer (password option), SharePoint (with access restrictions) or Google Drive (share with specific people) are safer than unprotected email attachments.