Hi All,
I have Exchange 2016 environment with Edge and Mailbox servers, Now Mailbox server have Third-Party certificate(GoDaddy) and Edge server running with self-CA certificate, recently we have some random scans over our email domain on https://ssl-tools.net/mailservers/ and https://www.checktls.com/TestReceiver and we failed on certificate category as below.

Detail error as below
Certificate #1 of 1 (sent by MX):
Cert is unsigned
Cert VALIDATION ERROR(S): unable to get local issuer certificate
This may help: What Is An Intermediate Certificate
So email is encrypted but the recipient domain is not verified
I suspected this due to self-CA certificate on Edge server, I hope Same Godaddy certificate were can't install on Mailbox and Edge server.
To over come this error Edge server also require a different Third-Party certificate? Please suggest me on this.