I'd really like to be able to let smime.p7s through the gateway.

Hello Shawn,

Thank you for contacting the Sophos Community!

What is the reason in Sophos Central email currently, that the emails with p7s are getting quarantined?

Regards,

Central is using True-File-Type Detection.

So actually the P7S will be looked at the real filetype is a certificate. See: https://stackoverflow.com/questions/21056781/how-to-get-mime-type-of-p7s-files

Its not actually p7s, instead it is using .der. So thats the reason, Central is not listing p7s. If you use a DLP rule for the cert types like der, it should hit by p7s files. 

DLP violation

Thank you Tony,

IMO If Sophos is going to call it P7s then it should be in the list as P7s.

Here is the current "Use Sophos list(recommended)" Certificates list, only .crt  is check marked. .der is not.

.arm
.cer
.cert
.crt √
.der
.p12
.pem
.pfx

I also need this fixed. It is a shame that we're blocking security measures that need to be implemented in email. Please provide a proper solution to not allowing all .crt, but allowing smime.p7s files.

Same situation. We are using Sophos list(recommended) View Sophos list. The p7s is not in the list of Sophos default blocked email attachment file types, but the gateway blocked it due to the Certificates reason. 

Can this be fixed?

Probably not.  Since they haven't done anything to fix it yet and I am still fishing the mails out of the quarantine manually.

THIS HAS NOT BEEN RESOLVED-

We need understanding of why we cannot use Email encryption on your platform.

Blocking all smime.p7s attachments is malarkey and you need to correct this problem!

This is one more reason I may just dump the Sophos Email gateway and use O365 filtering. We're right on the verge, as their system supports certificates correctly. I'd rather give money to Sophos, but we need some understanding of when we can expect this to be correct.

Hello,

This issue is being investigated and worked under XGE-17869, this is potentially going to be taken care of in a DLP coming in Q2/Q3 frame time, at the moment this is expected behavior.

Regards,