You have to set some environment variables, such as LANG, LC_CTYPE, LC_MESSAGES to your local language. Usually LANG (or LC_ALL) is sufficient. Note that modern distributions and operating systems do this for you automatically.

Yes. In Configuration->Common preferences, under the Display tab.

In Configuration->Common preferences, under the Display tab you can press the button Set display item of summary.... That pops up a screen with all the options you can show or leave out of the message list.

You can. In Configuration->Common preferences, under the Details and External commands tabs, you can define your editor of choice. Remember, if you want to use a command line editor like vi or emacs, to write the name of the shell (term, term, rxvt) with the -e parameter in front of the editor. E.g.: rxvt -e vi %s. Also, make sure that you have checked Automatically launch the external editor in Common preferences->Compose->Editor, if you want the editor of your choise to be launched every time you begin composing a message.

You can set the GTK+ font by $HOME/.gtkrc, or $HOME/.gtkrc.mine, (which is included by $HOME/.gtkrc). For example: style "default" { font = "-adobe-helvetica-medium-r-normal--12-*-*-*-*-*-iso8859-1 " } widget_class "*" style "default"

In Configuration->Common preferences, there's a checkbox Save sent message to outbox. Uncheck it, and it's solved.

That is very simple. Suppose you want to assign a shortcut key to a function, e.g. sending all mail out should start when you press Ctrl-Y. Click the Message menu and move the mouse over Send all messages. Now you press Ctrl-Y. Immediately the menu text is updated and the function is in place. Please note that a previous function that Ctrl-Y was assigned to, will no longer have a shortcut key. If you want to remove the key binding, do the same thing, but press the Delete key on the menu item. Then the key binding is removed.

Of course! Not all windows, but by pressing Escape, you can close the addressbook, the window of viewing a mail source (View->Message source), the window of viewing the headers, and several others. Just give it a try and you will find all of them.

As of 0.4.65 you can. The options are:

     %y = year in numbers     %m = month in number
     %d = day in numbers      %c = date/time for locale
     %A = full weekday name   %a = short month name
     %B = full month name     %b = short month name
     %H = hours in 24-clock   %I = hours in 12-clock

For more information, go to the Configuration->Common preferences->Display->General and choose the ... labeled button.

You need to enable displaying of the header pane in the general preferences.

You may not have compiled in Compface support. See the appropriate question in the Installation and Configuration section.

You need to double click the URL.

When you try to launch a helper application, like an image viewer, with an attachment that has spaces in the name, put quotes around the %s parameter. Example: gedit '%s'

Open Configuration->Preferences for current account...->Compose. There you can check the Bcc checkbox and optionally enter an e-mail address.