Release 6.20.0: Introduced white-list property to specify clients which are allowed to receive a notification about a new mail (mail-push)

[changerequest]

Due to fix bug 19688 we introduced a white-list property to specify clients which are allowed to receive a notification about a new mail (mail-push).

New .properties file mail-push.properties.

Property name com.openexchange.push.allowedClients.
Default value: USM-EAS*, OpenXchange.HTTPClient.OXAddIn*
(EAS and Outlook clients only)