One of the biggest complaints so far about Apple’s latest release of OS X is that in Safari, and especially Mail, all your previously saved RSS feeds are gone. This was a relatively popular feature, and many were left disappointed to find everything had disappeared, but fear not, as with this Terminal command you should have them back in no time (via MacGeneration).
1. Type this into Terminal:
cd ~/Library/Mail/V2/RSS/
2. Now paste this command:
find . -name "Info.plist" -exec grep -A 1 Feed {} \; | grep string | sed 's/^[^>]*>//' | sed 's/<[^>]*>$//'
3. You should now see all your RSS feeds listed in the Terminal window. Download a third party RSS client like Reeder (link) and copy/paste them into it, and you should have everything recovered and working.
Alternatively, you can also copy and paste them into Google Reader or any other RSS service, but do transfer them otherwise you can’t make use of them without constantly bringing up the Terminal.