Regardless of whether it's legal or not, it isn't terribly good netiquette
to publish third parties' contact details in a public forum - it increases
the chance of that third party turning up on the infamous spam lists, for
example, and some people do prefer to be the equivalent of ex-directory.
Mind you, it's also not terribly good netiquette to take someone to task
about things like this in public either - a polite note off list usually
Mea culpa etc.