The nation's biggest postal union removed an emotional albatross from around its neck today, voting against issuing an ultimatum to the U.S. Postal Service either to rehire 150 workers or face a crippling national mail strike next summer.

Amnesty for the workers -- fired more than two years ago following a wildcat walkout -- has been a major, often painful issue for the American Postal Workers Union. The amnesty question was a ticking time-bomb that threatened to overshadow wages, firnge benefits and job security issues on the bargaining table next year.

Militants had hoped to commit this union's 270,000 members to go out on strike unless the Postal Service -- which has said a flat "no" to amnesty -- rehired the workers to their Jobs in Northern California and New Jersey.

About 2,000 workers were cited by the U.S. Postal Service for participating in an illegal strike in July 1978. More than 200 were fired and 150 of those firings have been upheld by arbitrators. The strike was not sanctioned by major AFL-CIO unions who have been defending members, with varying degrees of vigor, ever since.

Instead of issuing an amnesty-or-else warning to the Postal Service, delegates voted a much tamer bargaining stance. It requires only that their contract negotiators make amnesty a "major concern," but not a strike issue. Had the militant position been upheld by this convention, it could have bound union negotiators to get amnesty and the new contract or call a strike no matter what other items were on the table.

The current three-year contract expires July 21, 1981. It has given most of Postal Service's 600,000 heavly unionized workers three annual pay raises, six cost-of-living raises, and protected everyone hired prior to September, 1978, from Layoffs for any reason.

Talks on the new contract begin in a few months. Postal officials have made it clear they want major changes in the no-layoff clause, major modifications of the twice yearly cost-of-living raises, and other expensive features. They have made it very clear there will be no amnesty for fired workers and high officials have hinted they were prepared to take a strike if necessary. That last obstacle, amnesty, has been removed by this convention.

The delegates here continue to plow through resolutions which, although often boring, are making major structural an financial changes in this AFL-CIO organization which represents Postal Service clerks and other workers.

Changes already approved by the delegates will force the union to spend an extra $700,000 to $1 million each year. APWU members pay less than $5 per month in national dues, a common figure in the government labor movement but a dues structure that is ridiculously low by private industry union standards.

Delegates learned today that the full-time officers they have added to service Puerto Rico and Alaska will cost $125,000 a year. By upgrading and adding new jobs for the motor vehicle craft members of the union costs will rise another $60,000 to $100,000. Various rebate plans sending dues from the national office back to local union treasuries will cost $180,000 a year.

Actions taken so far this week mean that the delegates will be asked to approve a per capita dues increase of between 25 cents and 50 cents per month. Officials said 25 cents would cover current costs, but the leadership wants an extra 50 cents a month -- from each of its 270,000 members -- to cover future inflation.