Hi Bill, thanks for pointing that out. That’s a bummer, really. This must’ve happened some time after Debian 8 entered End-Of-Life. I’ll update the article to include this warning, hoping that MailCleaner’s new release comes quickly.
I guess the alternative now is to perform the certificate validation on another machine and then copy it over. If you have a pfSense firewall, for example, this is really easy to do (I’m planning on writing a simple how-to about this).
Cheers,
Victor.