A name, domain, logo, and a draft website - this is the way MailMum was born out of an internal project.
To reduce the time to manage the blacklists through DevOps tools directly on servers and restart the email services after every change, we built our blacklists, which could diversify servers and this way and was fast enough to answer to handle all the requests without getting high system load and slowdown mail processing. At this point, every admin had his instance he could manage by using his favorite scripting language.