Affected version(s): all
Only E-Mails received within the last three days are synchronized to the mobile device, no matter what is configured on the device.
The default configuration of the ActiveSync implementation sets a limit to synchronize only E-Mails received at the last three days. This configuration is made at the server and overrides the device configuration. The setting is intended to keep the resource usage of ActiveSync connections low.
The limit can be set at /opt/open-xchange/etc/eas.properties with the property com.openexchange.usm.eas.mail.time_limit, the default value is 3. This configuration takes integer values like "3" to allow synchronization for E-Mails only newer than three days. Note that synchronizing very large mailboxes can produce some load at the mobile device, the devices' network connection and the server as well as the E-Mail backend. Since this setting is server wide, it should be set with caution. Typically this limit is only relevant for the initial synchronization, subsequent synchronization events will only synchronize new or updated E-Mails which typically generates negligible resource usage.