Privacy, in plain words

The claim is exact: your mail server cannot read a sealed message, and neither can we. Here is what that rests on, and where its edges are.

What is sealed, and where

When you send something sealed, your words and files are encrypted on your device under a key made for that one message. The encrypted bytes go to our file store. The key goes into the link, after the #, which browsers never send to any server. So the store holds bytes it cannot read; the email carries a link it cannot open.

The same is true of your own account. Your secret phrase never leaves your device. It unlocks one sealed record: your list of what you sent, your name and logo, and the private key that replies are sealed to. We hold that record as ciphertext and a hash that proves a device may write to it. We cannot read it, and we cannot reset a forgotten phrase.

What is not hidden

• That an email was sent, from whom, to whom, and when. The envelope is the mail system's.
• The subject line. Seal Pup writes a plain one ("A message from James") so yours stays sealed with the words.
• The size of what you sent, roughly, and the time it was stored.
• Which account a reply is for, so we can show it to you. Not its contents.

The link is the key

Whoever holds the email can open the message, exactly as with an ordinary email. So a sealed message is as private as the inbox it lands in. For the few messages where that is not enough, add a passphrase: three plain words you tell the person another way. The store refuses to hand the bytes out until the right words are typed, counts the misses, and rests the link for an hour after five.

Taking it back

Unsend deletes the sealed bytes. The link stops working the moment the store confirms they are gone, and Seal Pup only says "taken back" when it has that confirmation.

What we keep, and for how long

Sealed messages and files stay until you unsend them. Your account record stays until you close the account. We keep no copy of a message's key, ever. The carrier email, when Seal Pup sends it for you, contains the link and nothing else, and is not stored.

Cookies and analytics

None on the public pages. The app keeps your email address on the device so you do not have to type it twice.

Questions: hello@sealpup.app.