Mail footers tend to be a political, rather then a technical thing. Especially in germany, where federal laws tell you to include certain information into your mail footer, this is a major headache for every company. When things change, everybody has to alter the footer with a large number of users forgetting that.
Additionally, marketing departments like to misuse footers as an advertisement space for product offerings or events and force the users to regularly update their footer according to the new set of products.
After several requests I came across in the years of my employment for different companies, I finally sat down and created
[[http://dploeger.github.io/disclaimr/|Disclaimr – A mail disclaimer server]]
Disclaimr uses the widely adopted Milter API to „hook into“ the mail-process of mail servers, that support Milters (that’s basically every modern mailserver – sadly except exim as it seems). For configuration, it comes with a nice web ui, that enables non-tech-savvy stuff to work with it.