Update AD Users' Email Address from CSV where this field is empty in AD (except specific domain)

PSNewie2021summat like:

foreach($user in $Users)
{
    $adUser = Get-ADUser -Identity $user.AccountName -Properties EmailAddress -ErrorAction SilentlyContinue
    if($adUser)
    {
        # user exists 
        if([System.string]::IsNullOrWhiteSpace($adUser.EmailAddress) )
        {
            # email address is empty, set it
            $adUser | Set-ADUser -EmailAddress $User.Email
        }
        elseif($adUser.EmailAddress -like '*mycompany.com')
        {
            # Leave this email alone. 
        }
        else
        {
            # email address exists, what to do here?  
        }
    }
    else
    {
        # The user does not exist.  This is probably an error of soem sort. 
    }
}

Assuming the Get-ADUser line succeeds  of course.