You need to send a sensitive PDF. Two options: encrypted attachment or secure share link. Each has its place; here's how to choose.
Encrypted attachment
How it works: encrypt the PDF in Flint, email the file as an attachment, send the password through a different channel.
Strengths: simple, no third-party platform required, works with any email client, file is self-contained.
Weaknesses: once delivered, the file is in the recipient's possession permanently — no revocation. Email forwards forever. Larger files may hit attachment size limits.
Secure link
How it works: upload the file to a secure file-share platform (Dropbox, Tresorit, your enterprise system), share a link with the recipient, optionally with expiry and access controls.
Strengths: revocable, time-bounded, audit log of access, no attachment-size limits, can layer with platform access controls.
Weaknesses: requires the recipient to access via link, dependence on the platform's availability, sometimes blocked by corporate email filters.
When to use each
Encrypted attachment for: routine confidential documents (contracts, statements), one-off sharing, small files, recipients you don't share with regularly.
Secure link for: large files, recurring sharing, situations where you might need to revoke later, regulated material with audit obligations, anything where the recipient might forward.
For maximum security on high-stakes material: combine. Encrypted file via expiring link with audit log.
Practical patterns
Solo consultant sending an invoice: encrypted attachment is fine. Law firm distributing a court bundle: secure portal with link. Mortgage broker collecting client documents: secure portal with upload. Doctor sending a referral letter: encrypted attachment or NHS secure mail.
Match the workflow to the relationship and the risk.
FAQ
Is one objectively more secure?
Secure link with expiry and audit is more controllable. Encrypted attachment is simpler and self-contained. Both can be secure with discipline.
What if the recipient prefers attachments?
Many do — links require an extra step. For routine documents, accommodate the preference; for high-stakes, push for the link.
Do corporate email filters block encrypted attachments?
Sometimes — they can't scan encrypted content for malware. If filters block, use a secure link instead.
Can I use both?
Yes — encrypted attachment as backup, link as primary. Belt and braces for important sends.
Pick the delivery to match the file. Encrypt first in Flint; deliver via the channel that suits the relationship.