This bugs me enough on a regular basis that I think it is worth fixing it for good:
https://github.com/discourse/discourse/commit/ee0d3f15c1914bd494ebe88a5831d40be88bbcae
Our new default is that com|net|gov is autolinked, and http:// https:// is autolinked.
Apologies .uk and .au but I feel this new default is far saner and now sites have fidelity to expand or contract the behaviour.
Use: enable_markdown_linkify to enable or disable linkification globally.
Use: markdown_linkify_tlds to list TLDs you wish to auto-link if people forgot to add http[s]:// in front.
@codinghorror you happy with this?