There are two ways to file your tax return. You can file electronically--e-file -- or you can print, sign and mail your return. Email is not a way to file a tax return.
The IRS is not "closed"--but they are backlogged and are not opening mailed returns at this time. They will get to them later.
Per the IRS website IRS Operations During COVID-19: Mission-critical functions continue: The IRS is not currently able to process individual paper tax returns. If you already have filed via paper but it has not yet been processed, do not file a second tax return or write to the IRS to inquire about the status of your return or your economic impact payment. Paper returns will be processed once processing centers are able to reopen.