'You should have mail' for marriage poll

The Australian Bureau of Statistics says more than 16 million postal surveys have been sent to eligible Australians and they should have been received by now.

More than 16 million Australian should now have received their same-sex marriage postal ballots in the mail.

The Australian Bureau of Statistics says anyone who is yet to receive their ballot or needs a replacement should get in touch online.

"We're strongly encouraging people to post their completed surveys back to the ABS by 27 October 2017," Deputy Statistician Jonathan Palmer said in a statement on Monday.