We have users who have lots of mail rules, in fact more than 100. For this reason, they refuse to use Lotus Notes.
They are using Microsoft Outlook connector to connect to their Domino mailbox. This is a support headache for us, and we are limited in a lot of things we want to do in our environment because of this pocket of users.
Of all of the complaints and issues that they have with Notes, the one point that we can't argue with is the limit on the number of mail rules that Notes has, but Outlook does not.