Email delivery problem

shayser

I've got an email from HSE tech saying that the reason email's from us to them are being blocked by their mail server is because they are encrypted. We don't do any encryption. Encryption would hardly be added somewhere along the route, would it?

Sounds like a problem at their end? Should they be able to show me a text of the encrypted message?

seamus

It's possible that certain people are encrypting their mails before sending them. Are all mails being blocked?

The only other thing I can think is that they mean that your SMTP server is attempting to deliver mails over a secure connection rather than bog standard plain SMTP.

If everyone else is getting your email it sounds like a problem on their end.

shayser

It's a particular sender to a particular recipient that has the problem so I will look at this user's Outlook configuration (can't get access to their desk till lunchtime). Does the recipient need to be set up to decrypt the message and would they also need to be using Outlook?

seamus

Yes and no. Assuming that they're using PGP, then yes they would need to have decryption software and their own private key. They don't need outlook as a lot of PGP software is either standalone or can be integrated into any mail client.

What a lot of softwares do is store public keys against contacts in the sender's address book. What's probably happening is that your guy has his contact's public key matched to his email address and so every time he sends a mail to this guy, the email is encrypted.

Your problem is coming from the recipient's server - they're blocking the incoming mail because it's encrypted and presumably their AV/firewall rules say that if it can't be scanned, it gets blocked.

There are only two options really - your guy has to stop encrypting the mails, or they have to change something on their server.

shayser

Checked the guy's email, he has no encryption. Could it be some sort of false positive, like happens with spam?