I just tested it and it works.
I installed nodebb-plugin-sanitizehtml
, enabled it, and enabled HTML (from Plugins -> Markdown -> Allow HTML).
$ npm install nodebb-plugin-sanitizehtml
Then changed the settings for "allowed attributes" to:
{"a":["href","name","target","rel"],"img":["src","class","alt","title"]}
and "allowed tags" to:
["h1","h2","h3","h4","h5","h6","blockquote","p","a","ul","ol","nl","li","b","img","i","strong","em","strike","code","hr","br","div","table","thead","caption","tbody","tr","th","td","pre"]
Now this should work:
<a href="http://amazon.com/" rel="nofollow">Amazon </a>