At some point if you maintain different software projects you will be tired of managing emails with bug reports or feature requests from different users in different formats and and and… The solution is software called bug tracking software. There are a lot of small and big software packages out there and also for zero money (opensource/freeware). The main problem is to find the right solution. The first intention is usually bugzilla or something like that. But this might be overkill, especially for smaller projects or small number of customers.
One solution I tested and which I really can recommend is called „FlySpray“. Its a multiproject bugtracker/feature request tracker with multiuser support, email notification and easy to use web frontend. As backend you can MySQL. The setup itself takes about 10 minutes and you can start with tracking bugs/features.
More information is available at http://flyspray.org