Did smartermail change its web certificates? Today I am getting the following warning message from Thunderbird apparently asking me to change the digital certificate for my site email server (SMTP). I am not an expert on mail so I'm not sure if this is a hacker trying to take control of my mail server. Any advice is appreciated. Thunderbird screen shots Note: (my domain name is removed from the screen shot for security) If I click the "View Certificate" button I see this.