The U.S. Postal Service yesterday reported that for the fourth straight four-week period this fiscal year, its finances are in the black.

Postmaster General William F. Bolger, speaking before the monthly meeting of the postal service board of governors, said that for the last four-week period he had expected a $3.2 million loss instead of the $1.7 million profit. The postal service accounting procedures use four-week periods.

During the first quarter of this year, the postal service had profits of $163 million compared with $367 million last year. Blamed for the lower earnings were a 6.8 percent increase in personnel costs and 24.3 percent rise in transportation charges, which was higher than postal officials had expected, they said.

Last year the postal service earned $470 million, the first profit earned by the postal system since the end of World War II. Bolger said yesterday, however, that he still expects the postal service to have a deficit by the end of the year.

The board of governors was expected to discuss yesterday whether to implement the proposed electronic mail system, but the governors recessed until Feb. 22 when the subject will be taken up again, postal officials said.

The controversial electronic mail plan would allow mailers -- usually private companies -- to transmit computerized messages to post offices which would print the messages, place them in envelopes and deliver them within two days anywhere in the country. The service would be used primarily for heavy mail users whose mail is based on computerized lists, such as customers' bills.

In December, the U.S. Postal Rate Commission, which serves as a public forum for postal questions, recommended in a 3-to-2 decision that the postal service enter the electronic mail field.

But its decision would prevent the postal service from contracting with one carrier to transmit the messages. The rate commission recommended opening up the elctronic transmission function to more than one carrier.

At a House subcommittee hearing yesterday, however, two dissenting commissioners said that their colleagues' decision "relegates the service to performing data-processing and envelope-stuffing functions for the telecommunications industry if the industry chooses to participate."

Commissioners James H. Duffy and Kieran O'Doherty also hinted at tension among the commissioners over the decision, and said that they may not have been given full cooperation by the commission staff in getting briefed on the case and preparing their dissents.