We are currently using Office/Outlook 2010 and looking to roll out Office/Outlook 2016. An internal client mentioned that on his production (2010) system, when he gets an email with a digital signature he is able to open it and gets no prompts. There is
the signed tool tip once he opens the email that lets him know it is signed. When he tries this on his test system (2016), he gets a pop-up titled "Digital Signature: Invalid". There are three action buttons Details, View Message, and Close. If he
clicks on the View Message button it opens and again it just has the tool tip about the signature. He wants to know how he can disable the pop-up in 2016.
I had him forward the emails to me as attachments and when I open them in 2010 and 2016 I get the "Digital Signature: Invalid" pop-up in both. After doing some digging, I am supposed to be able to go into Details and then select Edit Trust,
go to the Trust tab, then select Explicitly Trust this Certificate. However, when I try this the Signer under the Message Security Properties is still listed with a "!". Also, as part of my testing I used OWA to open the message.
In OWA, when you open the message there is a notification that says...
Signed by: There were problems validating this signature.(More information)
If you click on (More information) you get a popup that says...
The digital signature on this message isn't valid or isn't trusted.
The digital signature on this message can't be verified. The sender didn't include the digital ID used to sign the message.
The signature is still well within it's valid time (doesn't expire until mid 2019), and comes from a well known and authorized CA.
So I my question is this. Why is his 2010 behaving differently than mine? Why can't I "force" Outlook to trust the cert? Can or should the "Digital Signature: Invalid" pop-up be turned off/disabled? Can this be addressed the same
way for 2010 and 2016?
Thank you
Outlook 2010 and 2016 Digital Signature Invalid
