function Get-SHDEXOMailboxSizeAudit {
    [cmdletbinding()]
    param (
        [pscredential]$Credential
    )
    Begin {
        
        #Installs required modules
        Write-Verbose "Installing required modules"
        if (!(Get-InstallEdModule ExchangeOnlineManagement)) { Install-Module ExchangeOnlineManagement }

        Write-Verbose "Checking and importing required modules"
        # Starts importanting required modules
        if (!(Get-Command Connect-ExchangeOnline)) { Import-Module ExchangeOnlineManagement }

    }
    process {
        
        #Connecting to exchange. Grabing credentials. 
        if (!($PSBoundParameters.ContainsKey('Credential'))) {
            $Credential = (Get-Credential) 
        }
        Connect-ExchangeOnline -credential $Credential
 
        #Grabs all the mailboxes at once. As this report will look at all the mailboxes. 
        $Mailboxes = Get-Mailbox

        #Starts looping through each mailbox
        For ($M = 0; $M -le $Mailboxes.count; $M++) {

            Write-Verbose "Gathering Info on: $($Mailboxes[$M].UserPrincipalName)"

            #Grabs the mailbox stats.
            $Stats = Get-EXOMailboxStatistics $mailboxes[$M].UserPrincipalName
            $FolderStats = Get-EXOMailboxFolderStatistics $mailboxes[$M].UserPrincipalName

            #Starts looping through those folders to get their sizes. 
            $MainFolderStats = foreach ($Folder in $FolderStats) {
                $FolderSize = [math]::Round((($Folder.FolderSize.split('(')[1].split(' ')[0] -replace ',', '') / 1gb), 2)
                [pscustomobject]@{
                    Name = $Folder.name
                    Size = $FolderSize
                }
            }

            #Adds this information to the mailbox object
            $Mailboxes[$M] | add-member -Name "Statistics" -MemberType NoteProperty -Value $Stats
            $Mailboxes[$M] | add-member -Name "FolderStats" -MemberType NoteProperty -Value $MainFolderStats
        }

        #Creates a return value. 
        $Return = foreach ($Mail in $Mailboxes) {

            #Starts looking at mailboxes that are not the discovery mailbox.
            if (!($mail.UserPrincipalName -like "DiscoverySearchMailbox*")) {

                #Grabs the deleted folder as that is a folder we want to see in this report. 
                $Deleted = $Mail.FolderStats | where-object { $_.name -like "Deleted Items" }

                #Grabs the largest folder. If  it's not the deleted folder, then we might want to increase their mailbox sizes.
                $LargestFolder = $Mail.FolderStats | Sort-Object Size -Descending | select-object -first 1 

                #Doing some math on a string. The string format (# bytes). Thus, we work the string to get the bytes. Divide and round. 
                $Size = [math]::Round(($Mail.Statistics.TotalItemSize.value.tostring().split('(')[1].split(' ')[0].replace(',', '') / 1gb), 2)

                #Grabs the mailboxes percentage.
                $DeletedToMailboxPercent = [math]::Round((($Deleted.Size / $size) * 100), 0)

                #Outputs the data to the return value. 
                [pscustomobject]@{
                    DisplayName             = $Mail.Displayname
                    UserPrincipalName       = $Mail.UserPrincipalName
                    MailboxSize             = $Size
                    LargetsFolder           = $LargestFolder.Name
                    LargetsFolderSize       = $LargestFolder.Size
                    DeletedItemSize         = $Deleted.Size
                    DeletedToMailboxPercent = $DeletedToMailboxPercent
                }
            }
        }
        
        #Disconnects exchange
        Disconnect-ExchangeOnline -confirm:$false > $null
    }
    End { 
        $Return | sort-object MailboxSize -Descending 
    }
}