The national sorority has responded on its Facebook page, saying, "Delta Gamma Executive Offices is aware of the email allegedly written by a member of our Beta Sigma chapter that has gone viral after being posted on gawker.com and deadspin.com. Right now the office staff is investigating the legitimacy of this letter, the alleged author and will take appropriate actions as necessary. EO staff is already in contact with the Beta Sigma chapter."
It's hard, on the website of a family newspaper, to correctly represent the tone and content of the email quoted. Here's an attempt at one small passage:
"I do not give a flying ----, and Sigma Nu does not give a flying ----, about how much you ----ing love to talk to your sisters. You have 361 days out of the ----ing year to talk to sisters, and this week is NOT, I ----ing repeat NOT ONE OF THEM."
But perhaps that's enough to give you an idea. Read the very very NSFW rest here.