Status from 'Case Received' to ' Document was mailed'

Received the below email alert from USCIS, but case status on USCIS website is Document was mailed. what does this mean?

There has been a recent processing action taken on your case.

Receipt Number: WACXXXXXXXX

Application Type: I129, PETITION FOR A NONIMMIGRANT WORKER

Your Case Status: Post Decision Activity

We mailed your document for your Form I129, PETITION FOR A NONIMMIGRANT WORKER, Receipt Number WACXXXXXXXX. If you do not receive your document by June 3, 2016, please go to www.uscis.gov/e-request to request that we resend the document to you. If you move, go to www.uscis.gov/addresschange to give us your new mailing address.

For approved applications/petitions, post-decision activity may include USCIS sending notification of the approved application/petition to the National Visa Center or the Department of State. For denied applications/petitions, post-decision activity may include the processing of an appeal and/or motions to reopen or reconsider and revocations.