Complex sentence: The Australian Marriage Law Postal Survey is a national survey to gauge support for legalising same-sex marriage being held in Australia via the postal service between 12 September and 7 November 2017.
Split into simpler sentences: The Australian Marriage Law Postal Survey is a national survey to gauge support for legalising same-sex marriage. The survey is being held nationally via the postal service between 12 September and 7 November 2017.