I have removed lot of topics from my forum. Google sent me message on Webmaster tools that there are problems with
Soft 404 errors
Google sent me some example pages of my Soft 404 errors: http:/my-website-forum/forum/page1475.html which redirect to the last page http:/my-website-forum/forum/page350.html
The problem is that the page http:/my-website-forum/forum/page1475.html should return 404 and not do redirect 301 as I understood from 'Soft 404 errors' document.
Do you know where should I do changes to return 404 code on http:/my-website-forum/forum/page1475.html?
Note, that I have already fixed my phpBB to return 404 NOT FOUND for deleted posts, because it returned HTTP 200 OK for deleted posts.
I am using phpBB SEO mixed 0.6.2 on phpBB 3.0.6