Right now, you can not e-file any 1040 returns for any return. https://www.irs.gov/e-file-providers/modernized-e-file-mef-status-page"1040 MeF Production Shutdown/Cutover Schedule
Shutdown begins on Saturday, November 17, 2018, at 11:59 p.m. in order to prepare the system for the upcoming Tax Year 2018 Filing Season."
When it re opens, you can file 2018, 2017 and 2016 (Current year and two prior). That means you will NOT be able to e-file 2015.