You cannot file an extension using Easy Extension with a foreign address. To use Easy Extension, a U.S. or APO/FPO/DPO address is required:
https://ttlc.intuit.com/replies/3301328
If you have a foreign address, then you will need to paper-file using Form 4868:
https://ttlc.intuit.com/replies/3301811
The deadline to file a tax extension is April 18th for most taxpayers.
Taxpayers who are out of the country are granted a two month extension, which means that
you can file for an extension at any time until June 18th:
https://www.irs.gov/Individuals/International-Taxpayers/Taxpayers-Living-Abroad
