You may not use any item brought to you on Shabbat from outside techum Shabbat.
Example
Even if a non-Jew brings you misdirected luggage sent on a flight that did not land until after sunset on Friday, you may not use the items inside until after Shabbat has ended, even if you need the items for Shabbat. Consult a rabbi for exceptions.

Techum Shabbat (Shabbat domain) is the furthest distance a Jew may walk on Shabbat. Wherever you are when you start Shabbat determines your starting point for techum Shabbat :

• City/Enclosed Area If you start Shabbat in a city or enclosed area of any type, you may walk up to 0.7 mile (1 km) beyond the border (last house) of that city or enclosed area.
• Uninhabited Area If you start Shabbat in an uninhabited place, such as a forest, you may walk only within a 0.7 mile (1 km) radius of where you started Shabbat.

If you are outside techum Shabbat (which may be as little as 0.7 miles, or 1 km, past the last house of an inhabited area—city, village, etc.), you may start Shabbat at sunset even if the nearby community starts early, as long as the rabbi from that community does not have authority over your area.
 

If an entire community starts Shabbat early, individuals must also start early.

You may not use, on a Jewish festival, any item that was outside the techum Shabbat when the Jewish festival began--even if a non-Jew brought it to you.
SITUATIONYou arrive on a flight but your luggage is delayed and delivered on Shabbat or a Jewish festival. Or, a package is delivered to you then.
WHAT TO DO  If the airport or delivery warehouse is within techum Shabbat, you may use whatever is brought to you. If the airport or warehouse is outside techum Shabbat, you may not use the items until enough time has passed after Shabbat (or the Jewish festival) for them to have been delivered from the airport or warehouse.

If your ship docks before sunset on Friday, you may get off on Saturday. Techum Shabbat is measured from the boat.

Do not bring mail inside the house on Shabbat, unless it was delivered:

• From within techum Shabbat, AND
• Within an eruv, AND
• By a non-Jew, AND
• Already open.

Reason Most mail is muktza since it cannot be opened or used without doing melacha.

You may bring a newspaper, magazine, or other reading material inside the house on Shabbat and read it if there is an eruv, unless it was:

• Brought from outside the techum Shabbat, OR
• Printed on Shabbat, OR
• Delivered by a Jew.

If any of these conditions apply, you may not use it in any way on Shabbat, even if all of the other conditions would have permitted its use. You may use it once Shabbat is over.

You may bring a newspaper, magazine, or other reading material inside the house on Jewish festivals and read it, UNLESS it was:

• Printed on Shabbat or a Jewish festival, OR
• Brought from outside the techum Shabbat, OR
• Delivered by a Jew.

If any of these conditions apply, you may not move it or use it in any way during the Jewish festival, even if all of the other conditions permit its use. You may use it once the Jewish festival is over.

Do not bring mail inside the house on Jewish festivals, unless it was delivered:

• Open

• From within techum Shabbat, AND
• By a non-Jew. 

 

The International Dateline (IDL), which is 180 degrees away from Greenwich, England, crosses the Pacific ocean from north to south and divides a region of safek/doubt as to which day is Shabbat. This region's eastern boundary is a line 180 degrees east of Jerusalem, which lies between Hawaii and the US mainland; the western boundary is east of Shanghai. All countries in this region of IDL safek/doubt are island countries.
 
In a region of doubt, such as Tasmania, keep normal Shabbat (Shabbat d'rabanan) on local Saturday and keep Shabbat d'oraita on:

• West of mainland USA, but
• East of the IDL, and
• Not attached to the mainland.

• West of the IDL, but
• East of Shanghai, and
• Not attached to the mainland.

Note In all cases, you must still observe regular Shabbat on Friday night/Saturday.
Situation
You are in a place near the International Dateline (IDL) in which you are not sure which day of the week it is halachically: Shabbat or, if you are east or west of the IDL, Friday or Sunday.
What To Do
On the Friday or Sunday in question, there is no shvut (d'rabanan prohibitions, including muktza), so you may do all melacha d'rabanan WITHOUT a shinui. You may:

• Ask or tell a non-Jew to do anything, including a melacha d'rabanan or d'oraita.
• Ride in a cab or car driven by a non-Jew.

• Use electricity--except for heat or light—including turning on a fan or air conditioner (heat and light are forbidden by the Torah).
• Use the telephone. (Using a cellphone may be permissible--ask a rabbi).

• Carry from a private domain (reshut ha'yachid) to another private domain, even through a public domain (reshut ha'rabim); but you may not stop walking in the public domain and you may not put the object down in the public domain unless you use a shinui.
• There is no practical way to light candles, even using a shinui, but a non-Jew may light them for you and and you may say the blessing on the candles.
• Swim, surf, scuba dive, climb, and play all games that do not use melacha. You may not wring out clothes and if you are swimming or scuba diving, your swimsuit or wetsuit must be clean.
• Walk any distance (there is no techum Shabbat d'oraita).
• Kinyan. You may acquire items.

• Fly, including check in and getting on plane if:
  • The pilot is non-Jewish, and
  • You don't do any melacha d'oraita (including any writing) without a shinui.
• Use a computer if it automatically goes to sleep after less than 24 hours of not being used.
• Shower. However:
  • You may not use an “instant on” hot water system in which the water is heated as you use it; you may only use the hot water if it has a holding tank.
  • You may use only liquid soap; hard soap is forbidden.
• Ingest medicine (but you may not smear it on skin).
• Use some make up, such as rouge, mascara, eye shadow. You may not use lipstick.
• Open a refrigerator with light (and all other psik reisha d'la neicha lei).

• You may buy necessities on Friday or Sunday as long as:
  • The store owner is not Jewish (or if he/she is Jewish, does not write or print a receipt),
  • You do not write, and
  • There is no reshut ha'rabim.

You may also do melacha d'oraita if:

• You use a shinui (non-normal way of doing that action--this is forbidden d'rabanan on Shabbat but is allowed on the Friday or Sunday in question), OR
• Two or more people do the melacha together.

 
D'oraita, you may not:

• Cook food.

• Turn on lights (but you may turn them off).
• Carry from domains.
• Boneh – building any permanent structure.
• Write two or more letters of the alphabet.
• Drive--there is no practical way to drive using a shinui.
• Shave--there is no practical way to shave using a shinui.
• Use toothpaste (but you may use tooth-cleaning powder).
• Use skin cream--you may dab it on without smearing it.

However, you may do these following actions with a shinui on the Friday or Sunday in question, as follows:

• Cook food. You must put food in the cooking utensil first, then turn on the heat with shinui. You may turn off the heat even without a shinui.
• Turn on lights (such as with your elbow).
• Stop along the way when carrying from a private domain (reshut ha'yachid) to another private domain, even through a public domain (reshut ha'rabim). As a shinui, you may carry the object in your mouth (as long as it is not food), etc.

Note Carrying something in your pocket is NOT a shinui.

• Tear paper (such as putting toilet paper across knees and moving the knees apart).
• Write (such as with the opposite hand).

Flying East From Australia on Sunday If You Cross IDL from Friday into Saturday

You may continue riding in a car or taxi driven by a non-Jew between sunset and dark (tzeit ha'kochavim) beginning a Jewish festival, even if the vehicle is driven just for you. You:

• May not do this on Shabbat.
• Must have already paid before sunset. 
• May not open a door that will cause a light to turn on or do any other melachot.
• If you have already traveled outside techum, you may move only 4 amot (85” or 116 cm) away from the vehicle, unless the driver leaves you off in an enclosed domain (any area surrounded by walls or an eruv), in which case you may go anywhere in that domain.
• If you had not gone outside of techum, you may go anywhere in the domain and you may also go up to 2000 amot (3,542 ft. or 1,080 m) outside of the domain.