When the U. S. Postal Service quietly removed 17 mail collection boxes from Silver Spring residential areas last month, outraged residents launched a campaign to get them back.

"Simple justice demands that the rape of the mailboxes be redressed," wrote Max Rosenfeld in his letter to Thomas W. Chadwick, the Postal Service's consumer advocate. He said that he had been using the box at the corner of East Melbourne Avenue and Mintwood Street for 31 years before it was "suddenly spirited away, along with all the other mailboxes on this side of Flower Avenue." Rosenfeld said that the "abrupt and unadvertised" removal of the boxes "leaves a neighborhood containing a large number of retired people without a mailbox they can safely walk to."

In another letter, Detta and Horace H. Harding complained that the "vaunted U. S. Postal Service descended upon our neighborhood like thieves in the night and removed many of the letter boxes which have been serving many of our neighborhoods for many, many years."

And Eleanor Torun said the removal of the boxes "now makes it necessary for people in my neighborhood to walk a considerable distance to mail a letter."

Last week the complaints paid off. Chadwick said the Postal Service had been wrong to remove the mailboxes and intended to replace them immediately--"and we will use overtime if necessary."

The promise came in response to a reporter's inquiries about the letters, which were written more than two weeks ago. Chadwick, after locating the letters in his file, contacted Fred McGuire, the manager of the postal facility that serves Silver Spring.

"McGuire said the community should have been consulted before the boxes were removed. . . so to put an end to the problem, we are replacing them," Chadwick said. He said that the Postal Service regularly audits the use of mail collection boxes and, if they aren't being used efficiently, removes them "to save on energy cost of collection and on manpower cost."

An average of 50 letters a day must be deposited in a box for it to be considered efficient under a Postal Service program instituted more than five years ago, according to Frank Brennan, a postal spokesman.

"What it comes down to is the population shift we have throughout the country. If a mailbox isn't being used efficiently, we remove it to a growing area where there wasn't a box," he said, "but we try to be good neighbors, and if a situation arises where the community feels there has been a mistake, we replace the box."