Custom colour in Outlook

OK here's a tricky one for you - how do you save a CUSTOM colour in outlook? I can create one in the message itself, and it works for that message. However, my next message reverts to the default, whatever I have selected in options. I go to options --> Mail Format --. Fonts, and cna change the colour, but cannot create a custom colour. I tried setting word as default editor, and modifying normal.dot - which worked for documents, but not for Outlook. Grrrrr.....