"What is defamatory?
A statement is defamatory if it tends to lower the plaintiff in the estimation of right thinking members of society generally. Alternatively speaking, the matter tends to make the plaintiff shunned or avoided by right-thinking members of society. The meaning of the defamatory nature of the statement can be literal or by inference.
By asking yourself the question, "would the person, group, or business named in your post, being a clearly identified entity, institute an action if he/she/it considered the posting to injure his/her/its reputation/standing if the posting were shown to be untrue."
While in slander damages have to be proven, in libel damages are presumed."