What is the site's stance on uploading doujinshi? I understand that paysite content is DNP, but what if the doujin has already been uploaded to another site (e.g. one specifically for doujins)? Is it still DNP if it's already on the internet for anyone to see?

Last time I checked, almost all of it would be considered paysite content unless it was uploaded by the artist to Twitter, Pixiv, or something. The fact that it was uploaded to a third-party that does not respect copyright (e.g. nhentai) does not change the DNP status.

I would consider collecting the titles and making a thread about them (but no links to third-party sites).