I found a problem with resolving username from email in function email2user (rcube_user.php). This function only resolves strict aliases like

user@example.com realuser

Especially, does not support %1 substitution and aliasing to another e-mail. By example, below entries aren't proprerly resolved.

user@example.com otheruser@expamle.com otheruser@expamle.com realuser

don't work for user@example.com

or

user@example.com realuser @another.domain %1@example.com

don't work for user@another.domain

I wrote a quick patch, that allow recursion in virtusertable processing and doing %1 substitution. In addition, enrties "cathall" like

@example.com user

ale supported.

This patch works for me, but are a rether non-optimal because i don't change anything in findinvirtual() function, and virtusertable is readed in every recursion. This can be fixed easyly by caching $virtual array.