They have discontinue this feature with this "update" to Mail 15 and it's unacceptable.
We use this feature every day for use in work so that we can view several pdf's information while composing that information into our email message. NOW, we have to select the pdf, click the space bar and pull the information, then select and space bar to close or x out. Then do this again with each pdf attachment when we have several (which is also a nightmare b/c file names are only shown partially so half the time I have to hover to make sure it's the file name I need, before doing the select and space bar to open). Why would apple change this? There was already a choice in the settings to NOT use this feature if you don't like it. JPEG and PNG STILL show up in a composing email, so why ruin it for PDFs? This was a MAJOR reason we switched to Apple Mail, it allowed us to do what a PC cannot, what's the point of using Macs and the Mail if you're just going to take those special features that make it worth it's value, AWAY. I'm tired of software designer changing things just to change them, almost always with a negative for users. We are administrators, we type and click millions of times per year. Not only has Apple taken away the benefit of being able to view the attachments automatically with no effort, before sending but they've increased the clicks to use be able to view them. Over a years time, how many extra thousands of clicks AND labor hours did Apple just cost us? To make things even more insulting, you can still view the pdf one pagers once the email is sent, a very valuable option to those that work in email and documents all day, so why remove the composing aspect at all? It makes no sense, is a burden on your customers, and it needs to be brought back in a new update!!