If using on windows you will need to get the binary file openssl. you will get the warning message on load up

you can also check the certificate details in outlook if it is faulty.

disable the SSL scanning and then recheck the ssl certificate is correct.

adding the account and re-adding it in outlook did not work.when you click install it is never installed permanetly (only if it is expired?).it is avast issuing a certificate from its system on the fly Security Certificate Errors Yahoo Mail Just Now Yahoo Security Certificate Expired XpCourse.i cannot find the certificate for .uk in my ssl store.re-installing the mail component does not fix this (including a reboot).The instructions below are what helped me come to that conclusion. As it happens the certificate at the other end was out of date and Avast mints new certificates on the fly so there is no cache to worry about. I had this issue with an SSL certificate that I thought was correct at the remote server and that Avast Antivirus had then flagged as out of date. Now if you examine the certificate: This certificate has expired or is not yet valid When using Outlook you can also see this error: The downside to this is that all certificates appear to be signed by avast! Web/Mail Shield Root and can make things confusing at first glance when a SSL certificate is out of date.

When you use Avast Antivirus it installs an invisible proxy SSL Certificate Authority that allows it to scan SSL/TLS traffic with its antivirus engine.

Yahoo mail and avast certificate error