They actually have two generic e-mail forms you can use...this one is from the download.com aspect while this one is from Upload.com. Note, however, that most questions concern malware, corrupted downloads, etc...things the technical team handles. In this case it would be forwarded to the editor(s) in charge or the reviews, and when contacting them there's rarely a guarantee you'll receive a response.
John
Hi,
I am the author of the software Plancoin, listed on Download.com. In the editor's review of this product are some suggestions to make it better. I would like to ask for some details about these suggestions. Where can I ask ? In a forum ? To an email address ?
Thanks for your response and sorry if I asked in the wrong forum.
Romain.

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