Some of you may have noticed that email messages created by using the “Send by Email” function in DEVONthink appear with a black background in Apple Mail on Mac OS X 10.6.4. This is actually a bug in the current version of Mail and also affects other applications apart from DEVONthink. Read more about it here. We hope that Apple will fix it soon.
Workaround for the moment: Switch the created email from rich text to plain text and back. This removes the formatting and so also the black background color of the text.
Update: Apple has posted an update to Safari 5.0.1 which fixes this problem. See here.