LOS ANGELES—In an impassioned 1,900-word open letter published in Monday's Washington Post, actor-director Sean Penn urged the unknown person who registered the e-mail address SeanPenn@gmail.com to "come forward immediately, rather than wallowing in the shame and ignominy of fraud."

Sean Penn

The paid full-page advertisement, addressed to "a certain inconsiderate asshole," continued: "Every American—indeed, every human being, regardless of nationality—deserves to be rightfully and accurately represented on the World Wide Web—the communication gateway into the next century and beyond—without having to resort to nonsensical aliases with random strings of numbers tacked onto the end. In an era of global wireless technology, our very identities are at stake. It's highly unethical at best, criminal at worst, for others to wantonly abscond with them."

Penn recounted in the letter how he had waited for an invitation to Google's e-mail service for a year and a half before receiving one earlier this month. According to Penn, when he tried to establish an account, he received a message indicating that his desired user name, SeanPenn, had already been registered.

"Sir or madam, if only you could have seen the anger and revulsion that washed over my face as I found that SeanPenn@gmail.com, Penn@gmail.com, SPenn@gmail.com, Penn.Sean@gmail.com, and SeanPennRules@gmail.com had all been taken," Penn's letter read. "If only you could have felt my heart leap to my throat upon realizing that Seanpenn@gmail.com would not work either, as Gmail addresses are not case-senstitive. If only you could have heard my cry of anguish when, in a last, desperate move, I typed in Spicoli@gmail.com, only to be rejected once more and finally forced to accept the abomination that is Sean.Penn20061@gmail.com."

Continued Penn, "It's a sad, sad day for the individual's right to self-determination and self-expression, let alone for the movie directors, journalists, and diplomats who will not be able to easily remember—or even recognize—my e-mail address."

Penn said he also tried SeanPenn81760@gmail.com, ShawnPenn@gmail.com, and SeanPennActor@gmail.com.

This was not the first time Penn has expressed anger over the difficulty of obtaining a Sean Penn-specific e-mail address. He made headlines last year when he refused to appear on the set of Columbia Pictures' All The King's Men for two days after he learned that SPenn@sonypictures.com had been taken by video assist operator Steve Penn.

Penn admitted that the painful experience of not being able to communicate freely through e-mail had its upside.

"Oh, certainly, I identify more strongly with the poor, war-battered youth of the Middle East."

Penn ended his statement by reiterating his demand that the SeanPenn user-name holder reveal his identity, assuring him that he will not retaliate with punitive measures or even ask that the e-mail address be relinquished. Instead, Penn invited the perpetrator to accompany him to Iraq, to "learn a hard, real-life lesson about the devastation wreaked by false pretense, gross injustice, and misapplication of power."