A have observed that email-threads has been copied into the comments of an issue. The thread was relevant to the issue, but the connection was lose, so it replacing the mail thread with comments was not possible.

Saving the thread as a .msg file and upload it would work to document, but viewing it will then require more effort.

A solution to this could be the possibilty of a view functions. One click on the .msg attachment will bring up a window displaying the email. This is similar to the preview of images, or the possibility to view files inside an uploaded zip file.