Etiquette for sending another email after the first one went unreplied
The important question is the interval between the time you applied and the time you expect an answer.  

If you applied on the day before the decision were announced it is quite possible there was not time to assess your file and sending another email will not help.

If on the other hand your documents were received months ago then another email or better yet a phone call if possible is not inappropriate.

Be mindful that applicants are often optimistic to expect academic decisions to be made within a few days of reception of documents.  Admissions officers may have to deal with 100s of files each containing multiple documents to be scanned so the information can be properly stored and distributed to appropriate faculty for later evaluation, and every link in the chain takes time.