21 Sep iOS 11 issues
With early adoption of iOS11, we are getting reports of some issues.
Outlook.com, Exchange, and Office 365 emails can’t be send. Most users are getting :”Cannot Send Mail. The message was rejected by the server.” It is well known issue and Apple is working on fix it with new update. If you already updated, we recommend on using Outlook app which is available at apple store.
Another issue is that 32 bit apps no longer supported. Therefore some of your apps will stop working.
We recommend on waiting few month before thinking about upgrading to iOS11.