Issue attachments can be selected by a checkbox to send them by mail or not.
The screen section is described with this text.
Select the attachments you want to attach to the email
Compare this screenshot.
New Feature: A preview of every (image) attachment is appreciated on that screen. Images may appear with a thumbnail.
When there are several attachments attached to one issue it is difficult to choose the right one for the mail. This gets especially complicated when the images have similar names, e. g. screenshot1.png, screenshot2.png and so on.