Mail Certificate Error

Try this again.

First time I hit post, forum ate the message, so dunno where it went.

Getting this dialog pop up when attempting to access Yahoo email via the Zimbra desktop program.

Was working fine up until today. With the mail shield off, Zimbra works as expected, turn the mail shield on, get this pop up, and though I can install the certificate into my local store, Avast refuses to let Zimbra access Yahoo.

And the “Confirm security exclusion” is grayed out so that option is not available either.

What, nobody knows what this is?

https://forum.avast.com/index.php?topic=161298.msg1155802#msg1155802

Appreciate the link, tis not it.

Some weird root certificate error on my machine:
Certificate *.imap.mail.yahoo.com
Designates
CN = Symantec Class 3 Secure Server CA - G4
as it’s authority.

The certificate states:
— quote certificate details panel —
This certificate has an nonvalid digital signature.
CN = Symantec Class 3 Secure Server CA - G4
OU = Symantec Trust Network
O = Symantec Corporation
C = US
— end quote —

I checked against the certificate at
https://www.tbs-certificates.co.uk/FAQ/en/Symantec_Class_3_Secure_Server_CA-G4_MPKI.html
and system claims it’s already installed.

I bet I figured it out:
What does the “This certificate has an invalid digital signature.” message actually mean?