Get email items from shared Exchange mailbox through Outlook. Can be modified to also output body (and other properties) of messages.

Get-SharedMailboxItems.ps1

<#
https://msdn.microsoft.com/en-us/magazine/dn189202.aspx
https://blogs.technet.microsoft.com/heyscriptingguy/2011/05/26/use-powershell-to-data-mine-your-outlook-inbox/
#>

Param (
    [Parameter(Mandatory=$true)]
    [string]$SharedMailboxEmailAddress,

    [Parameter(Mandatory=$false)]
    [string]$Subfolder
)

# Define constants
$PR_TRANSPORT_MESSAGE_HEADERS = 'http://schemas.microsoft.com/mapi/proptag/0x007D001E'

Add-Type -assembly "Microsoft.Office.Interop.Outlook"
$Outlook = New-Object -comobject Outlook.Application
$namespace = $Outlook.GetNameSpace("MAPI")


# Open shared mailbox
$recipient = $namespace.CreateRecipient($SharedMailboxEmailAddress)
$recipient.Resolve | Out-Null
If ($Subfolder) {
    $MailboxFolder = $namespace.GetSharedDefaultFolder($recipient, 
        [Microsoft.Office.Interop.Outlook.OlDefaultFolders]::olFolderInbox).Folders[$Subfolder]
} Else {
    $MailboxFolder = $namespace.GetSharedDefaultFolder($recipient,
        [Microsoft.Office.Interop.Outlook.OlDefaultFolders]::olFolderInbox)
}

# Parse mail items
$Items = $MailboxFolder.Items | Select ReceivedTime, Subject,
    @{N='SenderEmailAddress'; E={If ($_.SenderEmailAddress -like '*@*') {$_.SenderEmailAddress} Else {$_.SenderName}}},
    @{N='ToEmailAddress'; E={($_.PropertyAccessor.GetProperty($PR_TRANSPORT_MESSAGE_HEADERS) -split "`n" |
        Select-String '^To:\s+(.*)' | ForEach {$_.Matches.Groups[1].Value}) -split ',' |
            Select-String '<(.*@.*)>' | ForEach {$_.Matches.Groups[1].Value}}},
    @{N='CCEmailAddress'; E={($_.PropertyAccessor.GetProperty($PR_TRANSPORT_MESSAGE_HEADERS) -split "`n" |
        Select-String '^CC:\s+(.*)' | ForEach {$_.Matches.Groups[1].Value}) -split ',' |
            Select-String '<(.*@.*)>' | ForEach {$_.Matches.Groups[1].Value}}}

# Return
Return $Items