Support for resolving aliases to get actual login name.

[BtbN]

In my mail-setup, i never use my actual username as an e-mail address.
Instead, I use aliases.

I would be very nice if there was optional support for something that tries to resolve %u to an alias, putting it into another macro, %a or something like that, or setting said macro to %u if no alias was found.

Finding an alias is simple enough by executing "getent aliases %u". If it finds an alias for that name, it returns a line in the format "alias: username".

There also seems to be a python module for querying getent:

https://pypi.python.org/pypi/getent

With that, it shouldn't be much more than getent.aliases(username).