Try installing the "RCDefaultApp" preference pane:
http://www.rubicode.com/Software/RCDefaultApp/
Free, and it seems to do what it's supposed to.
If you try it, please post back to let us know if it worked for you!
I tried going to mail preferences and selecting outlook as the default, doesn't seem to work, when i click on an email address, it still opens apple mail.
Well.... El Capitan is already buggy enough - can you confirm that it works with 10.11?Why don't you try the RCDefaultApp pref pane I recommended above?
Thanks HenryAZ - it works!!!
Edit - It just opens new emails in Outlook, but if I want to send out a word document, for instance, it starts mail...
I spoke to fast unfortunately