Man, ther was so much "legalese" in that article I couldn't make hide nor hair of it. I did get, "lawyers want to sue". Sue for being offended, if I read correctly. Scary.
You're correct that the article was not very clear.
This article at law.com does at better job of telling the story: http://www.law.com/jsp/article.jsp?id=1112864716980
Here's an excerpt:
"This was a hateful and racist e-mail that verbally assaulted one of our staff members. And we have a responsibility to protect our staff and to respond appropriately," said Shearman & Sterling spokeswoman Jolene Overbeck.
A lawyer with the Electronic Frontier Foundation, a nonprofit that advocates for civil rights in cyberspace, says suits against anonymous Internet users are common now.
Most often, the plaintiffs sue for defamation for something posted on an Internet message board, then use subpoenas to try to figure out the author's identity, said Kurt Opsahl, a staff attorney at the San Francisco-based nonprofit.
Shearman & Sterling's suit is a little different. Rather than focus on the posting under craigslist's Rants and Raves section, the firm is basing trespass and breach of contract claims on the e-mail its staff manager received -- at his "shearman.com" account.
By sending the e-mail to a Shearman address, "Jane Doe deliberately and wrongfully misused and caused the continuing misuse of Shearman & Sterling's Internet resources," the suit contends.