What is the difference between deleting and archiving email messages? When should I delete and when should I archive?
If you either delete or archive a message, it’s removed from your inbox.
If you delete a message, it’s placed in the Trash and then permanently removed from your Google Apps account after 30 days.
On the other hand, if you archive a message, it’s moved to All Mail (your archive), where you can easily find it in the future, using Google’s powerful search feature.