I am the maintainer of a project which has a large non-technical userbase. I've been maintaining it for about 4 years now and adding new features as they've been requested.
I'd like to move on to other projects now and stop developing for this application. Because of the non-technical nature of the users, there have been very few code contributions in the past. I don't believe I will be able to find anyone else to take over the project in my stead.
Bugs, issues, feature requests - these are still coming in. I am still responding to emails for help, as I am not sure if I should ignore them, tell them that I'm not working on the application, or if I should respond to emails in only certain cases.
What is the best way to 'abandon' this project, but still let users use the application?
Update (July 2016) - It didn't go as planned. I made an announcement in the README and soon after, I started receiving contributions of a more substantial nature. Pull requests with bug fixes, features, documentation, issue activity. Since then, the project has felt 'reinvigorated' and I'm now happily maintaining it along with newer projects. I have collaborators as well. At a guess, it may have been the kind of contributions which were affecting my view of the project and with the quality of contributions improving, it didn't feel like a chore any more.