For Google Apps Groups – Standard Edition
In Google Apps, you can make groups and can even add external recipents. But there is a limit to no. of external recipents that can be send via groups also.
From one emailaddress you can email to not more then 1000 external recipents. After this quota is finished you will get an error message:-
Technical details of permanent failure:
The domain ___ has exceeded its quota for the maximum number of external recipients.
Then if you want to still send group messages to external recipents then you need to use a different sender address.
Hope this is clear. Please ask if you have any questions