Unable to retrieve ‘sender’ from mail message

[cnbatch]

When the mail was sent from a mailbox by another user (aka ‘on behalf of’, like ‘[email protected] on behalf of [email protected]’), ews-cpp cannot retrieve the ‘sender’ ([email protected]) section on this mail, ‘sender’ shows blank when get_sender().value() was called. Only ‘From’ ([email protected]) section can be retrieved.

In Microsoft's EWS Managed API, ‘sender’ can be retrieved correctly.

Exchange Server's version read by MS API was Exchange2003 SP1, the same as ews-cpp set in the code.