I have missed some email attachments due to overlooking the addition of the scrollbar in the message. I know that I can also hover over the message icon to get an attachment count, but it isn't habit since I usually don't receive multiple attachments. To prevent this in the future, I've set an alert for all email messages with attachments (overkill!) until I can train myself to look for these hidden (to me) attachments, but I really wish there were an easier way to catch these.