I recently implemented the strict htaccess rules generated by the Akeeba Admin Tools utility.   I then discovered that it was not possible to use Windows Live Writer to post entries to the blog anymore.   It was obviously a problem with the htaccess rules since a simple test removing the htaccess file enabled a post to complete successfully.

Looking at the configuration in more detail the most obvious cause appeared to be two rules related to access the xmlrpc directory:

RewriteRule ^xmlrpc/(index\.php)?$ - [L]
RewriteRule ^xmlrpc/ - [F]

But these rules permit access, they do not deny access. so they were obviously not the cause of the problem.

Then the light dawned.  There was a rule to redirect www addresses to non-www addresses:

RewriteCond %{HTTP_HOST} ^www\.(.+)$ [NC]
RewriteRule ^(.*)$ http://%1/$1 [R,L]

Because the Windows Live Writer (WLW) blog account was set up before the htaccess setting were changed it was set up to use the ‘www.xxxx’ address NOT the ‘xxxx’ address.

For this reason the posting was being disallowed.   The redirection was getting in the way.  Just disabling this one rule enabled the posting to proceed.  It was desirable to have the rule in place, so once I had changed the WLW blog account to use the non-www address posting could resume and complete successfully.

I hope others find this interesting and perhaps do not spend as much time as I have trying to resolve it.

I thoroughly recommend Akeeba Admin Tools Professional as a user since it has stopped SPAM on the site almost completely.  That alone is a triumph.