Merrill Lynch is subpoenaing an Internet service provider and Microsoft in an effort to identify the sender of “explicit racial remarks” in e-mail messages to black investment bankers within the company, a spokesman for the investment bank said.

The bank filed a trademark infringement lawsuit on Tuesday in U.S. District Court in Manhattan against the unknown sender, called “John Doe” in the documents, for impersonating an existing Merrill Lynch regional administrative manager by using a Hotmail e-mail address and signing the e-mails with the manager’s name, which was withheld in the suit. The e-mails, which began arriving in September, were also sent to the Reverend Al Sharpton and contain racial remarks directed at black employees, according to the complaint.

A spokesman for Merrill Lynch, Mark Herr, said in a statement that the company will subpoena the sender’s Internet service provider and Microsoft, which owns Hotmail, in an attempt to disclose information about the identity of the sender. The company suspects the e-mails originated from the Midwest.

“Merrill Lynch has sought to foster an inclusive workplace environment that promotes mutual respect, acceptance, cooperation, and productivity among people from varying backgrounds,” the suit says.

The “fraudulent e-mails have not only cast the Merrill Lynch employee whose name has been used for these racially explicit emails in a negative light, they tarnish the reputation and good will associated with the Merrill Lynch name and mark,” the complaint says.

Rev. Sharpton, who said he has seen a sharp increase in threats and hate mail this year, said he hoped the Merrill Lynch lawsuit would encourage law enforcement officials to investigate this kind of incident, which he characterized as a hate crime.