Get ALL Mailboxes via EWS (Exchange WebServices) - not my own but also shared and group mailboxes - directory

Question

Can anyone provide me with a .NET (C# / VB) sample of how to get all mailboxes that I have access to ?
I have only been able to get my OWN mailbox via EWS - not ALL THE OTHER mailboxes that I also have access to through Outlook.
I don't have the names nor the id's of these mailboxes but isn't it possible to retrieve ALL mailboxes - including my own - that I am allowed to see - just as I can in Outlook ?
I am using Autodiscover to get my mailbox like this: service.AutodiscoverUrl("xxxx#ee.dd") - this will perhaps only get my own mailbox and not all the rest?
Please help !?

Answer 1

The way I got around this was to define the group mailbox in question as a "mailbox" object and then obtain the FolderID for the particular folder.
Define mailbox object
Mailbox gpmailbox = new Mailbox("mailbox#yourdomainname.com");
Get the FolderID (in this case, the Inbox)
FolderId gpInbox = new FolderId(WellKnownFolderName.Inbox, gpmailbox);
Use FolderID in your normal code (in this case I'm obtaining 100 messages)
ItemView view = new ItemView(100);
FindItemsResults<Item> results = hookToServer.FindItems(new FolderId(WellKnownFolderName.Inbox, gpmailbox), view);
The key is to grab the FolderID of the folder you need. Hope this helps.
Edit: I also failed to note that my object "hookToServer" is simply the ExchangeService object. Here's how I defined it:
ExchangeService hookToServer = new ExchangeService(ExchangeVersion.Exchange2010_SP1);
hookToServer.UseDefaultCredentials = true;
hookToServer.Url = new Uri("TheExchangeServer")
I also used this as reference:
EWS 2007 Group Mailbox Guide

Answer 2

You can do this by Using Autodiscover to get user settings, this is a completely separate service to the one with the AutodiscoverUrl method.
The setting name you need is AlternateMailboxes, this will give a collection of all the 'other' mailboxes you have access to. You might then add the user's default mailbox to get a complete list.
In c#:
using Microsoft.Exchange.WebServices.Autodiscover; // from nuget package "Microsoft.Exchange.WebServices"
internal List<string> GetAccessibleMailboxes()
{
AutodiscoverService autodiscoverService = new AutodiscoverService("outlook.office365.com");
autodiscoverService.Credentials = networkCredential;
var userSmtpAddress = networkCredential.UserName;
GetUserSettingsResponse userresponse = autodiscoverService.GetUserSettings(
userSmtpAddress,
UserSettingName.AlternateMailboxes);
var alternateMailboxCollection = (AlternateMailboxCollection)userresponse.Settings[UserSettingName.AlternateMailboxes];
var smtpAddressList = alternateMailboxCollection.Entries.ToList().Select(a => a.SmtpAddress).ToList();
smtpAddressList.Add(userSmtpAddress);
return smtpAddressList;
}