From B2evolution

b2evolution version 2.5

The External Feeds fieldset is part of the Advanced Blog Properties since b2evo version 2.5.

This is useful when you use an external service such as Feedburner to manage your RSS feeds.

In this case, enter the URL(s) of your RSS2 and/or Atom feed in the appropriate field(s).

On subsequent accesses to your RSS2/Atom feeds, your readers will me automatically redirected to the aforementioned URLs.

ATTENTION: Your external feed provider still needs to access the b2evolution feed as a source for data. But, now, if it tries, it will get redirected to its own external URL. This is a chicken and egg problem. How do you solve it? Simply by asking b2evolution not to redirect in this particular case. So if your public feed URL was:

http://example.com/blog1.php?tempskin=_rss2

the URL you would give to Feedburner as a source would be:

http://example.com/blog1.php?tempskin=_rss2&redir=no

(just add &redir=no at the end of the URL)