How do I pay for tnefDD?
tnefDD is free software licensed under the GPL. You can use it for free as long as you abide by the terms of the GPL.
However, if tnefDD has helped you, you should make a donation to the project. This allows the tnefDD project, and others like it, to be developed further. You can make a donation at tnefDD at SourceForge.net, by clicking on the donate link. Note that you have to create a SourceForge user id in order to donate.