I have tried many plugins, which are doing the thing I want, but they are blocking my other plugins (1 in particular, which is indispensable for my site). Anyhow; how can I add a nofollow on all my outgoing anchors? Can someone help me out please?
This is how I would do it :
1/ create a filter to access the post content before it's displayed on page. See http://codex.wordpress.org/Plugin_API/Filter_Reference/the_content
2/ Inside your fonction called (ie : my_the_content_filter in the example from the Codex) adapt this code : https://stackoverflow.com/questions/5037592/how-to-add-rel-nofollow-to-links-with-preg-replace