Either solution will be equally effective. You can e-file the request for extension at the irs.gov website. Or you can print and mail Form 4868, making certain that it is postmarked before midnight on Monday, April 15, 2019.
Mailing addresses for Form 4868 can be found here: https://www.irs.gov/filing/where-to-file-addresses-for-businesses-and-tax-professionals-filing-form-...
