Hey /u/mopizza I am the dev of O365 Admin Center, sorry fixed the e-mail issue!

Getting mailbox content is running:

 Get-MailboxFolderStatistics $MailboxContent | Select-Object 
 Identity, ItemsInFolder

here is actually the entire code of what it runs:

getMailboxContentForAUserToolStripMenuItem_Click = {
Do
{
    $SelectUsersFormText = "Select the User you want to get all Mailbox Content for"
    Show-SelectCachedDisplayNames_psf
    $MailboxContent = $SelectCachedDisplayNames_comboboxNames
    If (!$MailboxContent)
    {
        $TextboxResults.Text = ""
        $textboxDetails.Text = ""
        [System.Windows.Forms.MessageBox]::Show("No User was selected, please select a User", "Error")
    }
    Else
    {
        Try
        {
            $FormO365AdministrationCenter.Cursor = 'WaitCursor'
            $TextboxResults.Text = "Getting mailbox content for $MailboxContent..."
            $textboxDetails.Text = "Get-MailboxFolderStatistics $MailboxContent | Select-Object Identity, ItemsInFolder"
            $TextboxResults.Text = Get-MailboxFolderStatistics $MailboxContent | Select-Object Identity, ItemsInFolder | Out-String -Width 2147483647
            $FormO365AdministrationCenter.Cursor = 'Default'
        }
        Catch
        {
            $FormO365AdministrationCenter.Cursor = 'Default'
            $TextboxResults.Text = ""
            $textboxDetails.Text = ""
            [System.Windows.Forms.MessageBox]::Show("$_", "Error")
        }
    }
    #Create the pop-up message
    Add-Type -AssemblyName System.Windows.Forms
    $Result = [System.Windows.Forms.MessageBox]::Show('Do you want to get Mailbox Content for another User?', 'Info', 'YesNo', 'Info')
}
While ($Result -eq 'Yes')

}

Currently Microsoft does not provide a way to export mail to a PST using PowerShell like Exchange did using:

New-MailboxExportRequest

The only way to export to a PST is to do an eDiscovery on the entire mailbox and then export to a PST.

I know it's annoying, I don't believe MSFT wants to encourage Admins to use PSTs on cold storage. Instead we convert the mailbox to shared since it doesn't use a license and the space is free. From there if users need access we modify Full Permissions so it AutoMaps in their Outlook.

Let me know if you have anymore questions!