1- Can't add new email on some mobile devices "iPhone and Android" after add email, password, server and domain showing error "unable to support"
NB.: Not for all users also not for new email, sometime old email log out and can't login again
App used on mobile: Outlook Connection: ActiveSync Exchange 2016 CU 18
2- Not receive any notifications on the mobile, knowing the notifications are allowed from the settings. (All users).
3-Have shared mailbox the user in shared mailbox have (Full Access and Send As) but can't send to more than 15 recipients, knowing I check (mailbox features ---> Mail Flow ---> Recipient limit) is unlimited.