Hello,
I suggest using Web access to your email if possible; the attachment is only removed on the way from the mail server to the mail client, so on the server that holds your mail it is still present; I am not aware of a way how to force mail client to redownload mail aside from removing the impacted account and re-adding it with Mail Shield disabled. Unfortunately such email parts are not present in chest.
Kind regards,
Ondrej Kolacek