Message Waiting Indicator (MWI) notifications are being sent for remote-only configured mailboxes.
When a mailbox is set to vpim_msg_del_pref = 1 (Remote only), a notification message is emailed to the recipient when they receive a new message. However, the system is also sending out an MWI message to the user's phone.
Resolving the problem
Download and install UM PTF fix level 18.104.22.168, and then use mwi_config with the -R switch to prevent mailboxes with vpim_msg_del_pref set to 1 having MWI turned on. For an example:
To show what settings are currently in use on the system:
To allow MWI notifications to be sent for remote mailboxes:
Note: This also removes the MWI number-length checking specified with -only -l, so you have to set those again.