Reading the posts, looks like there is no consensus on this issue. I chose the side of the family instead of the company. The Marine is gone and is in no pain, his family is. Yahoo has nothing to gain or lose in this. I view this e-mail issue as no different than any of his other personal effects that are left to the next of kin. A lawyer FReeper has posted the legal hurdles he went thru with AOL in a similar situation. In the end, he won. I hope the family of this Marine does , too. Sure, there may be things in there that he may have wanted to be private for whatever reason. But, I believe his family needs and deserves the access to his e-mails.....
An account is different from other personal effects because it is an intangible thing. Unless the man printed out the messages and left them with his other things, the messages should remain private.
We don't know the relationship between the man and his family, or how much access he'd want to give them to his personal account. He signed up under a privacy policy that blocks this sort of sharing, and unless he contradicted it himself, we should assume he wanted his privacy respected.
The family may 'need' access to his account in thier own minds, but it's not thier decision.
I just counted. So far, twenty one people (including myself) are clearly against Yahoo and the family violating the son's privacy. Three people, including yourself, appear in favor of abusing his trust. Eight people do not make their view clear, though four of those seem to lean against Yahoo breaking their obligations.
Why stop at Yahoo? Since he was a Marine I'm sure he had an official military e-mail account. Should they see those e-mails also? Most folks have more than one free account so should Yahoo, MSN, AOL etc be forced to do a search for all accounts he may have opened? Maybe he was a Freeper should they have access to that account also? They'll lose big time if this makes it to court.
I just fear that this may be a case of not being careful (as they should be) of what they wish for. Prayers for the family.