Attachment Area in UIxMailEditor.css is too small and contains no scroll bars. So it is impossible to check if the selected attached files are the right ones as the original names are not visible

This could be fixed by changing width in that file (300px is a minimum)
or by adding scrolling in this css box.

div#attachmentsArea
{ display: none;
float: right;
width: 120px;
padding: 2px 5px 0;
margin: auto;
border-left: 1px solid 0000888; }

There is another problem, it could be very useful to add a link to the original location of the attached file. While a user writes a message and add attached files, he could reopen the attached files and check if they are the good ones.