I also believe that the current 'theme' for the conversation header wastes some space, I might be wrong, but I think that a proper patch for this would be in the file Config.py, but this won't overwrite your current config, so you need to delete that manually, or apply the changes in the file /home/USER/.config/emesene1.0/YOURMSN/config on the convHeaderTheme line. As stated by the thread creator, if the personal message is too long, you won't be able to see the email. So probably a better approach would be '<email> Personal message' instead of 'Personal message <email>'.
--- Config.py (revision 1461)
+++ Config.py (working copy)
@@ -118,7 +118,7 @@
'receivedFilesDir' : '~/',
'disableEsc' : False, # disable the esc key to close conversations
'disableFormat': False,
- 'convHeaderTheme': '%nick%\\n<span foreground="%pmColor%">%pm%\\n%email%</span>',
+ 'convHeaderTheme': '%nick%\\n<span foreground="%pmColor%">%pm% <%email%></span>',
'autoAcceptTransfer': False
}