Import-Module MSOnline
$O365Cred = Get-Credential
$O365Session = New-PSSession –ConfigurationName Microsoft.Exchange -ConnectionUri https://outlook.office365.com/powershell-liveid/?proxymethod=rps -Credential $O365Cred -Authentication Basic -AllowRedirection
Import-PSSession $O365Session
Connect-MsolService –Credential $O365Cred

Get-MailboxFolderStatistics -Identity "TargetMailBoxID" | Select FolderType , Name , ItemsinFolder

#Target MailboxID's
$MailboxNames =  "TargetMailID"
#Any Exchange Admin ID with appropriate permissions
$AdminID = "AdminID"
#Fetch password as secure string
$AdminPwd = Read-Host "Enter Password" -AsSecureString
#Load the Exchange Web Service DLL
$dllpath = "C:TempMicrosoft.Exchange.WebServices.dll"
[Reflection.Assembly]::LoadFile($dllpath)
#Create a Exchange Web Service
$Service = New-Object Microsoft.Exchange.WebServices.Data.ExchangeService([Microsoft.Exchange.WebServices.Data.ExchangeVersion]::Exchange2013_SP1)
#Credentials to impersonate the mail box
$Service.Credentials = New-Object System.Net.NetworkCredential($AdminID , $AdminPwd)
foreach($MailboxName in $MailboxNames)
{
#Impersonate using Exchange WebService Class
$Service.ImpersonatedUserId = New-Object Microsoft.Exchange.WebServices.Data.ImpersonatedUserId([Microsoft.Exchange.WebServices.Data.ConnectingIdType]::SmtpAddress, $MailboxName)
$Service.AutodiscoverUrl($MailboxName,{$true})
#Assing EWS URL
$service.Url = 'https://outlook.office365.com/EWS/Exchange.asmx'
Write-Host "Processing Mailbox: $MailboxName" -ForegroundColor Green
#Fetch Root Folder ID
$RootFolderID = New-object Microsoft.Exchange.WebServices.Data.FolderId([Microsoft.Exchange.WebServices.Data.WellKnownFolderName]::Root, $MailboxName)
$RootFolder = [Microsoft.Exchange.WebServices.Data.Folder]::Bind($Service,$RootFolderID)
#Create a Folder View
$FolderView = New-Object Microsoft.Exchange.WebServices.Data.FolderView(1000)
$FolderView.Traversal = [Microsoft.Exchange.WebServices.Data.FolderTraversal]::Deep
#Retrive the Information
$response = $RootFolder.FindFolders($FolderView)
$response | Select DisplayName , TotalCount , FolderClass
}

using System;
using System.Collections.Generic;
using System.Linq;
using System.Management.Automation;
using System.Management.Automation.Remoting;
using System.Management.Automation.Runspaces;
using System.Security;
using System.Collections.ObjectModel;
using System.Text;
namespace Office365
{
    class Program
    {
        static void Main(string[] args)
        {
            string username = "ExchangeAdminID";
            string password = "Password";
            System.Security.SecureString securepassword = new System.Security.SecureString();
            foreach (char c in password)
            {
                securepassword.AppendChar(c);
            }
            PSCredential credential = new PSCredential(username, securepassword);
            WSManConnectionInfo connectioninfo = new WSManConnectionInfo(new Uri("https://ps.outlook.com/powershell"), "http://schemas.microsoft.com/powershell/Microsoft.Exchange", credential);
            connectioninfo.AuthenticationMechanism = AuthenticationMechanism.Basic;
            //connectioninfo.AuthenticationMechanism = AuthenticationMechanism.Basic;
            connectioninfo.MaximumConnectionRedirectionCount = 2;
            //connectioninfo.MaximumConnectionRedirectionCount = 2;
            using (Runspace runspace = RunspaceFactory.CreateRunspace(connectioninfo))
            {
                runspace.Open();
                using (PowerShell powershell = PowerShell.Create())
                {
                    powershell.Runspace = runspace;
                    //Create the command and add a parameter
                    powershell.AddCommand("Get-Mailbox");
                    powershell.AddParameter("RecipientTypeDetails", "UserMailbox");
                    //powershell.
                    //Invoke the command and store the results in a PSObject collection
                    Collection<PSObject> results = powershell.Invoke();
                    foreach (PSObject result in results)
                    {
                        string createText = string.Format("Name: {0} Alias: {1} Mail: {2}", result.Properties["DisplayName"].Value.ToString(), result.Properties["Alias"].Value.ToString(), result.Properties["PrimarySMTPAddress"].Value.ToString());
                        System.IO.File.WriteAllText("C:\User.txt", createText);
                    }
                }
            }
        }
    }
}

$Folder.Delete([Microsoft.Exchange.WebServices.Data.DeleteMode]::SoftDelete)
$Folder.Load()