I have a Philippine passport and have an Australian tourist visa issued, but I do not have a stamp in my passport. I am leaving tonight. Will I be ok to travel without the stamp in the passport?
You do not necessarily need a gummed sticker in your passport to travel to Australia. The letter will normally be sufficient.
Airlines that have authorization to land passengers in Australia are required to have a computer connection to Australia's immigration authorities. Before you board the airline, they will log in and receive a verification. If you have a visa, the computer will indicate such and you will be permitted to board.
If you flag up as not having a valid visa, the airline will not allow you to board. In that case you have been scammed and should contact your police.