I have users that have upgraded to IOS 10.0.2 on their iPads.
Now it's no longer possible to send a new mail from within WebAccess in Safari.

It works fine to login and read mail, butwhen clicking on button "New message" it justs blips, and no new message is shown.
After that the webpage is "locked", ie you cant scroll upp and down in the mails.

Works fine in IOS 9.x.
Cannot tell if it is the same in IOS 10.0 and 10.0.1 (down have any device to test on...)

GroupWise running GW 2014 R2, build 124742, dated 2016-09-07, ie quite new.