All doors lock automatically when the lock side is pressed. They unlock when the unlock side is pressed.
Driver's door

Front passenger's door

To lock all the doors from an open front door, press the lock side of the door lock switch and then close the door.
NOTE
When locking the doors this way, be careful not to leave the key inside the vehicle.
Locking, Unlocking with Transmitter
Auto Lock/Unlock FunctionMazda 6 Owners Manual: Registering Your Vehicle in A Foreign Country (Except United States and Canada)
Registering your vehicle in a foreign country may be problematic depending on
whether it meets the specific emission and safety standards of the country in which
the vehicle will be driven. Consequently, your vehicle may require modifications
at personal expense in order to meet the regulation ...
Mazda 6 Owners Manual: Engine removal/installation
Warning
Fuel vapor is hazardous. It can very easily ignite, causing
serious injury and damage. Always keep sparks and flames away from fuel.
Fuel line spills and leakage are dangerous. Fuel can ignite and
cause serious injures or death and damage. Fuel can also irritate skin and
eyes. ...