We have conferences that require guest speakers and they send us their PowerPoint presentations via email. Until recently this has not been an issue. Most are less than 10MB in size and they are not zipped, usually. Recently we are receiving them, we find out when the speaker calls and asks if we received there presentation. Neither us, or the sender receive any notification that the email has not been delivered. I have checked the spam filter attachment settings and it is set to forward attachments up to 200 MB in size. No changes have been made in Exchange, any ideas what I can check?