/home/username/.mailrcYou should then carefully edit it to reflect your mail configuration (very few changes eg changing the sound file which is played when mail arrives to something else eg an audio file (xxx.au) in /usr/dt/appconfig/sounds/C )
Alternatively click on the mail-tray icon in the CDE tool bar and configure it using options All the recommended settings are provided for the 11 sections - but you need only do 3 to get started You can if you wish copy the and then fine tune it using CDE mail "Options" menu.
Here is a linked list to all 11 menus in the order in which they appear under "Options"
Here are all 11 menus in the order in which they appear under "Options"
Move Menu Setup