Shemiras Halashon Halachos

Hilchos Lashon Hara chapter 7, section 9

If the speaker is mesi'ach lefi tumo (speaking lashon hara conversationally without deliberate intent to divulge information - this is defined in the Beér Mayim Chayim comentary) the law is as follows: If the story even if true can be judged favorably or if it involves lack of good traits or other details explained above in paragraph 7, or if the speaker did not see the incident himself but heard it from others, it is certainly forbidden to believe the report. Even if one of these things does not apply one may not believe the story and one may certainly not repeat it to others or insult the person spoken of. Even more so, one may not cause him financial loss or strike him, G-d forbid. This would be a Torah prohibition.