The e-mail list of the Public School 290 PTA is a useful source on matters like fund-raising, after-school programs and the rules for the talent show coming up. It is not known to provoke strong feelings.

But the message that went out at the wee time of 2:18 a.m. on Jan. 16 disturbed many of the parents who bothered to read it. “You should read this book! It is rocking my world!” read the message, floating over a book’s cover. The cover had a dark Star of David at the bottom, the Nazi flag at top and the title in between: “Debating the Holocaust: A New Look at Both Sides.”

The sender, Michael Santomauro, whose son is in third grade at P.S. 290, on the Upper East Side, said Tuesday that it was not until minutes later, when two parents replied with complaints, that he realized his mistake. He meant to send the message to another group he belongs to, where members debate whether accounts of the Holocaust are exaggerated, and he apologized to the parents for the “total confusion.”

Still, the damage was done, and school officials and parents, many of whom are Jewish, were stunned not only by the e-mail, but also that there was such a parent in their midst.

The principal, Sharon Hill, called Mr. Santomauro to ask if his e-mail account might have been hijacked, or a virus had taken control of his computer, and he told her what had taken place.