When using a domain hosted by Google Apps, you will not have the option to make abuse@ or postmaster@ messages under your domain. Have no fear there is a way around this. Just follow these easy steps and you will be up and running in no time!
First of all, you need to make groups titled ‘postmaster’ and ‘abuse’. Now users that are part of these groups will receive emails sent to those addresses (i.e firstname.lastname@example.org)
Google has created an extensive list of directions showing you how to make groups.
They can be found here: https://support.google.com/a/answer/33343#adminconsole