SPEAKING OF strikes and settlements, peace in the Post Office has not come cheap -- and you can rest assured now that the 18-cents stamp is not long for this world. Still, a close look at the tentative settlement that seems to have averted a nationwide postal strike shows there is actually less to it than meets the eye; the additional money granted to postal workers in this latest agreement, while generous by any standards for comparable work, is not outlandish when productivity gains and new limits on overtime, premium-shift and holiday pay are taken into account.

Besides, in an economy so intricately built around the mails, there is something to be said for -- and gained from -- avoidance of a nationwide breakdown of all postal service. True, strikers could have been jailed and the military deployed to the office mail chutes, but the obvious as well as hidden costs of such a communications collapse might have been enormous. After all, even in a sophisticated computer-machine age, the machines that extend, cut off and manipulate consumer credit aren't programmed to understand or forgive people whose payments haven't been made because their checks are in the struck mails.

The most inflationary part of the agreement is the continuation of what is referred to as "full COLA" -- which is not some sort of diet drink, but a cost-of-living adjustment of pay to match any increases in the Consumer Price Index. Over the three-year life of the last contract, this formula produced a raise of $3,619 for each postal worker. Under the new agreement, the only other increase in the current average annual salary base of $19,915 would be $300 a year, or about $6 a week.

Certain bonus payments tied to ratification of the agreement and to productivity gains would be one-time-only and not included in the basic wage or in calculating overtime, shift differentials, holiday pay or retirement benefits. So if inflation were to continue at the same rate as it did during the last contract, the average base pay of a postal worker might increase by about $6 a day.

If this puts a little more zip in your letter carrier's gait, or a little more courtesy and enthusiasm behind those windows in the downtown branches where lines of customers have been known to petrify, all the better. Otherwise, postal workers can expect -- and deserve -- increasing resentment of their relatively secure and well-compensated status by those who foot the bills.

And what about the future costs? Postmaster General William F. Bolger is optimistic, pointing out that productivity has been rising. Since 1971, when the Postal Service was created from the old Post Office Department, productivity has been increased by 34 percent, with more pieces handled by relatively fewer employees. Also, in the next few years, attrition, through a wave of retirements, is expected to be significant.

Even so, there are limits to how high the price of that first-class stamp should go. Shouldn't more of the burden be taken on by those classes of mail other than personal correspondence, educational materials and periodicals? mMuch as we all dearly love our old friend and roommate, "Occupant," the mail for this popular person is getting out of hand as well as out of pocket for too many individuals.