^ *([\w_]+(?: *[\w/_\-\: ]+)? *) *(?:\[ *([\w_]+(?: *[\w/_\-\: ]+)? *)* *(?:\( *([\w_]+(?: *[\w/_\-\: ]+)? *|\b(((\S+)?)(@|mailto\:|(news|(ht|f)tp(s?))\://)\S+)\b) *\))?\])? *$

Not my largest regex by any means, but it looks complicated :)