Subscribe By Email Doesn’t Work

I have the powerpress plugin installed, here is an example page:

http://www.hvac-hacks.com/podcasts/txv-instead-tev-csv/

Click subscribe then by email.

Goes to this page:

http://subscribebyemail.com/www.blubrry.com/feeds/hvachacks.xml

This is displayed on the page: Not available in podcast directory.

However if you add an s for https instead of http the link works. I can’t figure out why it would link to the unsecure version therefore making the link unusable?