Calendar Sync Rules on the NotifyLink Administrative Web provide an option to select the conditions under which invitations are deleted from the device.

It  is recommended that ActiveSync devices be configured to delete all invitations from the Inbox to which the user has responded.  This option provides the most consistent expected behavior on ActiveSync devices.  Other options may not consistently delete invitations as expected according to the rule.

1.  From the Administrative Web, select User Administration.

2.  Select the ActiveSync device user and click Edit User Policy > Calendar Sync Rules

3.  Under Delete Invitations From Device, select All Responded from the drop-down list.