iOS Mail wont open zip files
After my test (ipad air 2 with 9.3.2) i see that MAIL opens only zip files produced with a MAC OS X.
With MAIL we can't open zip files produced on other operating system /app (for example windows or 7zip on windows, etc)
So their info 
("Supporto allegati email/Tipi di documenti visualizzabili" on https://support.apple.com/kb/SP708?viewlocale=it_IT&amp;locale=it_IT)
are not true (or are partially true)