Comparison

The comparison in detail

Eight tools, the same six questions – and the reasoning behind every answer.

The short overview is on What tunnl. is for. This is the same table in full, to read and to pass on.

tunnl.

Built for exactly this: once there, then gone.

Can the provider read it?	no Encryption happens in the browser. The key sits in the link behind the #, and browsers never send that part to a server. What lies on our machines is gibberish.
Where does it sit afterwards?	nowhere The first message is deleted once opened – not flagged as deleted. There is no second copy sitting in a mailbox.
Does it go away by itself?	yes You choose the pick-up window. If nobody picks it up, the message expires. Conversations end 30 days after the last activity.
Second lock via password?	yes Set a password and pass it along another way. Without it the link is useless to anyone, us included. After 10 failed attempts the conversation deletes itself.
Does the other side set anything up?	no No account, no app, no invitation. Open the link, read, reply – on a phone as on a computer.
Still changeable?	yes While nobody has opened it, you can change text and files. The new version overwrites the old one on the server.

E-Mail

The default route: reaches everyone, costs nothing – and multiplies everything.

Can the provider read it?	yes Both providers and every stop in between see the content. Encryption exists only if both sides have set up the same scheme – which is rare.
Where does it sit afterwards?	all over Your mailbox, theirs, both backups, often an employer archive. Whoever later gets access to one of them reads everything in hindsight.
Does it go away by itself?	never Both sides must delete, and nobody does. Deleting your copy achieves nothing.
Second lock via password?	DIY A password-protected ZIP works – but the password usually goes in the next mail, and the attachment still sits in both mailboxes.
Does the other side set anything up?	no Everyone has a mailbox anyway, and you usually know the address already. That is mail's real strength.
Still changeable?	no Sent is sent. All that remains is the second mail with an apology.

WeTransfer

The file courier: closest of the bunch, but no lock and no secret.

Can the provider read it?	yes The file sits readable with the service. It is not end-to-end encrypted.
Where does it sit afterwards?	with the service Up to 3 days on the free and Starter plans, indefinitely on Ultimate. Branded pages stay up longer.
Does it go away by itself?	yes An expiry date is part of the product – the key difference from mail.
Second lock via password?	paid Password protection exists only in the paid plans.
Does the other side set anything up?	no A link is enough. Which is also the problem: it is enough for anyone who has it.
Still changeable?	resend You send a new transfer – the old link often stays valid until it expires on its own.

Teams / Slack

The work channel: built for ongoing work, not for secrets.

Can the provider read it?	yes Content sits in your company tenant. Admins and legal can reach it through eDiscovery.
Where does it sit afterwards?	in the channel The history is the point. It stays until a retention policy kicks in – set by IT, not by you.
Does it go away by itself?	policy Automatic deletion exists only where the organization configured it. Usually it has not.
Second lock via password?	no Whoever is in the channel sees everything. There is no second lock for a single message.
Does the other side set anything up?	yes Outside the company it needs guest accounts and approvals. Your customer will not install Teams for an invoice.
Still changeable?	traced Editing works but leaves an “edited” marker – and depending on policy the old version is kept.

The quick line: strong in transit, weak afterwards.

Can the provider read it?	no The end-to-end encryption in transit is good – better than most business tools.
Where does it sit afterwards?	on devices The document lands in the photo gallery and the history, the history in a backup. That backup is encrypted only if both sides switched it on.
Does it go away by itself?	optional Disappearing messages exist – but they must be switched on, and they apply to the whole chat.
Second lock via password?	no Whoever holds the device sees everything. A single message cannot be protected separately.
Does the other side set anything up?	yes App and mobile number – and business post then runs over your private number.
Still changeable?	briefly Deleting works within a time window. Afterwards a placeholder remains, and the other side has seen it anyway.

Cloud-Link

OneDrive, Drive, Dropbox: right for working together, clumsy for handing over.

Can the provider read it?	yes The provider holds the keys and can read the file – and logs who opened it when.
Where does it sit afterwards?	in the drive Along with version history and recycle bin. And the folder next to it is often shared as well.
Does it go away by itself?	optional An expiry date can be set – it is just usually forgotten. Otherwise the link lives until someone tidies up.
Second lock via password?	partly Password protection depending on provider, plan and the organization's settings.
Does the other side set anything up?	often Either the other side has to sign in – or the share is “anyone with the link”. Neither is pleasant.
Still changeable?	yes Replace the file, the link stays valid. The cloud does this better than anything else here.

IncaMail

Electronic registered mail: built for proof, not for disappearing.

Can the provider read it?	trusted third party Swiss Post operates the service and processes the message on its systems. That is deliberate – a signed receipt needs a party that can witness. It is therefore not zero-knowledge.
Where does it sit afterwards?	delivered stays delivered The message reaches the recipient and stays. With registered mail that is precisely the point.
Does it go away by itself?	no Registered items have a seven-day acceptance window; after that they count as not accepted. The content does not dissolve, though.
Second lock via password?	sign-in instead of password Protection runs through the recipient's account, not a per-message password you can pass on separately.
Does the other side set anything up?	yes The recipient must sign in to read. The sender needs a premium account or a business contract.
Still changeable?	no Posted is posted – that, too, is part of registered mail.

Proton Mail

The serious peer: encrypted and Swiss – but a mailbox, not a tunnel.

Can the provider read it?	it depends Between two Proton accounts, and for a password-protected mail to outsiders, Proton cannot read the content. An ordinary mail to a foreign mailbox is protected only in transit.
Where does it sit afterwards?	in the mailbox Proton is a mailbox and behaves like one: what is sent stays with both sides until someone tidies up.
Does it go away by itself?	only with an expiry An expiry can be set for password-protected mails. It is not the default.
Second lock via password?	yes The password for outsiders is well solved and part of the product.
Does the other side set anything up?	for full protection yes End-to-end between accounts requires the other side to be on Proton too. Otherwise the password route remains.
Still changeable?	no Sent is sent, as with any mail.

As of September 2026. Details on other providers follow their public documentation; what applies in Teams, Slack and the cloud also depends on each organization's settings.

Write a confidential message Back to What tunnl. is for · How tunnl. works