The postal vote compromise is a political fix to fulfill an election promise for a plebiscite, which right-wing Liberal MPs including former prime minister Tony Abbott want.
The traditional plebiscite and postal votes would not be legally binding if it's shown that most Australians support legalizing same-sex marriage.
He also confirmed Labor would move to legalise same-sex marriage within 100 days of winning government, even if the postal survey returned a winning "no" vote.
"Keeping promises is money well spent", Morrison said after the idea of a plebiscite - or public vote - was rejected by the Senate on Wednesday.
"However, the editorial policies also state that we should not offend our audiences without editorial justification and we should not be seen to condone or encourage prejudice and discrimination".
Sen. Nick Xenophon said his minor party's opposition had not changed since they opposed the plebiscite in the November vote.
"This is typical of the way Shorten plays the politics of this, I have been a supporter of gay marriage much longer than him - for a start", Mr Turnbull told 3AW. The result of the postal vote would not be binding on members of the Australian Parliament.
Finance Minister Mathias Cormann said overseas Australians could register at an overseas address and receive a ballot. "If you don't like same-sex marriage, vote "no", he told reporters. Other developed nations may be surprised to hear that in 2017 we are still politicking about people's human right to marry in Australia.
Deputy Labor leader Tanya Plibersek insists the best possible option is a free vote in Parliament this week or next.
He says no private member's bill will go to parliament without giving the Australian people a say, as promised at the 2016 election.
THE debate around same-sex marriage is raging again and it seems everyone has an opinion.
Some lawmakers argue the issue could be resolved with a simple vote in Parliament, but Turnbull's government seeks to gauge public support first.
Kirby who has been with his partner Johan van Vloten for 50 years will boycott the vote.
But the voluntary postal plebiscite, which looks the most likely scenario - will be a costly exercise, with no guarantee of marriage equality in the end.
"I think it is important that the debate does not divide our community", he said.
If the people of Australia approve amending the marriage act that is enshrined in the constitution, by way of a constitutional referendum to include the marriage of same sex couples, so be it. The point I am making is that the provision of equality under the law for same-sex couples to marry has nothing to do with forced adoption or stolen generation.
The union had been contacted by a number of ABS staff concerned about the agency's ability to conduct a plebiscite, given its regular work and capacity constraints, she said.