SSL Security Error
From MozillaZine Knowledge Base
This article applies to Firefox, Thunderbird, Mozilla Suite and SeaMonkey.
- If you make a secure connection to a server which domain does not match the domain name in the SSL or TLS certificate it uses, Security Error: Domain Name Mismatch is displayed to alert you of this. You should verify what server you are connecting to. However, this most frequently occurs when a site changes their domain name but doesn't buy a certificate for the new domain.
- If the SSL or TLS certificate is expired, Security Error: Server certificate expired will be displayed.
In both cases you can can get rid of the alert (for this certificate for this domain) by installing the Remember Mismatched Domains extension. It adds a “Don’t warn me again about this certificate for this domain" checkbox to the Domain Name Mismatch and Expired Certificate warning windows.