Plugin email Sql Encryption Symmetric Key Error

Hi,

I am getting some kind of Encryption error when I try and send an email in a plugin (action). I have two environments that are the same.  It works in dev but when I deploy it to a UAT environment, i get the following error whenever the plugin tries to create/send an email. Neither environment is HTTPS.  A lot of posts online say to go to Settings->Data Management->Data Encryption but that box will not open as its not HTTPS.

Cannot open Sql Encryption Symmetric Key because Symmetric Key password does not exist in Config DB

If anyone has any pointers that would be awesome.

Thanks,