What is generally considered the threshold for submitting articles before triggering duplicate content problems? If you submit the same article to 100 article directories, is that ok? Or should there be variations even for just 100 article submissions? Can you get away with sending the same article to 50 article directories? What are your thoughts on the number of directories you can submit the same article to?
Ezine will not accept dulplicate content,what u can do it get your article approved first at ezine and then u may subnit to other directories,try to submit unique article or u can always rewrite articles and submit.
Don't worry about duplicate content. Too many people are worried (misinformation) about the duplicate content 'penalty' from Google. If you want to increase search engine traffic with articles then submit them to as many sites as you can. This will increase the number of back links to your site which will help you rank higher in Google for your keyword terms.
I think at least 10 is ok...also think good to put on as many sites as you can as long as it is worth the time.