There's one possible correspondence from USCIS that would not come by email, and that is an RFE. They notify you by email that one is coming, but you won't know what's in it, unless it is received by mail.
There are a couple other times in the process, where a US mailing address is useful, in completing later forms. In this case, a simple official forward order (to a US Address) is probably sufficient. USCIS is not very efficient at changing petitioner addresses.