Lesson 1 There is an opinion that if someone spoke lashon hora in the presence of 3 or more people and they subsequently repeat this information, they are not guilty of speaking lashon hora. The reasoning is that when as many as 3 people are aware of something, we assume that it definitely will be spread, and according to this opinion, something that will become common knowledge is not prohibited as lashon hora.
Lesson 2 - continued from above NOTE - that is a lenient opinion and isnt accepted with most authorities. Even when its accepted (that you can repeat info said in the presence of 3 or more people), there are numerous qualifications that restrict its applicability. Even if all the conditions are met, which is extrmeeley rare, the Chofetz chaim remains in doubt as to whether this opinion can be relied upon. To be continued.