I just discovered that procmail website (http://www.procmail.org/) is down. I did some research about its status and it appears that the development of procmail has been dead since 2001. Even the old procmail maintainer recommends to remove it from openbsd ports because the code is in not safe (https://marc.info/?l=openbsd-ports&m=141634350915839&w=2). This is a bit scary, because unfixed bugs could lead to a remote code execution exploits. Recent Linux distributions (e.g. Ubuntu, Debian) still provide it, but is it still safe to use procmail?
You are correct that Procmail hasn't been maintained for a while, and its last maintainers suggest using alternative tools like Maildrop or Sieve.
The reasons many distributions haven't seen this as a real security risk include:
So, yes and no. If you have any concerns in your environment, you do have alternatives.