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An established financial institution just directed me to email them a document with sensitive information. When I questioned the security, the CS rep and manager both tried to assure me that, "because their system is secure", email to them is secure.

Is this really possible?

Other details:

  • I called them, not vice versa.

  • The manager added that, in order to really be secure, I would need to delete the message from my sent items.

zwiebelspaetzle
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    Here's a good related answer. https://security.stackexchange.com/a/30244/113999 – nbering Apr 12 '18 at 20:05
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    One thing I've done with financial institutions in the past that helps a little, is insist on sending them the content as an encrypted PDF, sharing the password over the phone. It's not enough to protect from a full wiretap or anything like that, but most PDF readers understand encryption, so they don't need anything fancy like a PGP mail client. A lot of web servers also block zip files or send them to spam. At least it's encrypted over the wire. – nbering Apr 12 '18 at 20:11
  • That's like saying that because you've swept your office for bugs, you know your phone is being tapped. – Acccumulation Apr 12 '18 at 20:40

2 Answers2

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No, email in general is insecure. Each server that relays an email necessarily gets a copy, and encryption is opportunistic, so you can't even guarantee that it'll be encrypted between relays.

Deleting it from your sent items would only help if your account gets compromised.

AndrolGenhald
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  • I agree. I'd like to add that there are some things you can do to disable the opportunistic TLS behaviour. For example, here's a help article for GMail. Your mail server needs to support this though, and it still doesn't ensure that their mail server (or any relays between) store it securely. Just that it's secure in transport. https://support.google.com/a/answer/2520500?hl=en – nbering Apr 12 '18 at 19:59
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I know some email services that encrypt incoming email. You upload your public PGP key, and when an email arrives, they encrypt it and then store it using your public key. It works like the sender uses PGP, but then at a later stage. When you download the mail via POP3 or IMAP, you need your private PGP key to decrypt the mail. Without your private key, the mail is lost.

Of course before the encryption has been done, and the original email has been properly deleted, everything is the same as with normal email.

As a side note: I've heard people state that their work email was "safe". This was in the health care business. Then they're probably talking about a web based system for taking notes, keeping records of clients, and clients get a login and can send messages inside the system. How safe is that? I can't tell, but probably safer than the average Joe User with no idea about safety handling his own email and antivirus.

SPRBRN
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