Start by checking if your RSS Email Campaign is active.
Your RSS Email campaign will not send out any emails if no new content is found. You can verify this by checking the "lastBuildDate" or the "pubDate" attributes in your RSS Feed.
An example is given below.
<?xml version="1.0" encoding="UTF-8"?>
<rss version="2.0" xmlns:content="http://purl.org/rss/1.0/modules/content/" xmlns:rdf="http://www.w3.org/1999/02/22-rdf-syntax-ns#">
<channel>
<title>Benchmarkemail Blog</title>
<link> http://www.benchmarkemail.com/blog/feed </link>
<description>Email Marketing Services - Create and send bulk HTML email campaigns & online surveys w/ Benchmark</description>
<pubDate>Mon, 03 May 2010 08:43:09 GMT</pubDate>
<item>
<title><![CDATA[Pointers for Those Who Prefer to Write Their Own Html Code]]></title>
<link>http://www.benchmarkemail.com/blogs/detail/pointers-for-those-who-prefer-to-write-their-own-html-code</link>
<pubDate>Mon, 03 May 2010 08:43:09 GMT</pubDate>
<description><![CDATA[When you create and send an email, plenty of factors determine whether your email makes it to the inbox.]]></description>
<guid isPermaLink="false">http://www.benchmarkemail.com/blogs/detail/120</guid></item>
</channel>
</rss>
