The stock mail handler classes included in JIRA aren't capable of issue creation across the set of all projects using a single service config. The commercial JEMH plugin is certainly capable, but is overkill for the simple case.
The Aliased Mail Handler supported use case is issue creation across all projects. The handler enables "routing" to specific projects by way of a regular expression that is matched against the recipient's address. This plugin works well for anyone using the relatively common aliasing pattern "username+mailbox@domain.com" supported by providers like gmail as well as SMTP servers like postfix.
The plugin doesn't do much more than that. It's a very simple use case and a very simple implementation. Feel free to send me pull requests for any enhancements here: