First of all, you need to create a list of websites that you want to track using Apple Mail client. Here, you should make the list of only those websites that offer the option to read RSS feeds.
Now visit the first website in your list and click the RSS feed icon or the syndicated link present on the page, to access the page. Copy the URL of the RSS feed page and paste it to the clipboard. Repeat the process for each website in your list.
Now you need to go to the “Applications” folder present in your Macintosh hard drive and double click on the Apple Mail icon to launch the email client. Before you proceed to adding RSS feeds to your Apple Mail client, you should make sure that you have an active email account running.
At the Apple Mail’s menu bar, you need to click the “File” option and select “Add RSS Feeds” from drop-down menu that just appeared.
A new window will open your screen, where you need to click the “Specify a custom feed URL” button, to add a new RSS feed.
Now you need to copy the link of RSS feed for the first website in your list and paste it in the “RSS Feed URL” section. If the RSS feed URL is correct, then the new blog posts will start appearing in the “RSS” folder, listed among the mailboxes present at the left side of the Apple Mail window.
You can now repeat the process from step 4 to step 6, for each website present in your list.