It would be nice to be able to write longer e-mails there just isn't enough space to get a detailed message across, second to be able to see all of your world wars not just the last ten.
Longer alliance messages would be amazing... as would personal messages. And fixing the donation bugs. Tbh, a chat system overhaul would not be out of place here.
I highly doubt they will ever change it so all your historical wars are displayed. For me, the first time in each session you open "World War History" there is significant lag. If there were 50+, it might take too long to load.
I also agree- the inbox space doesn't allow for very much to be said whatsoever. Functional links are also an excellent idea. Larger WW histories may get too laggy, I do see that now as well; but it would be awesome if we could download our history somehow and store it ourselves.
You'll never get enough support, as only co-leaders and leaders can send mail. So it doesn't effect that many players. Pinned chat messages in chat Boom Beach style would be great too...