Unite had threatened strike action over pay, pensions and modernisation.
Paul Reuter, national secretary of Unite, told BBC Radio he hoped the deal would help Royal Mail and the Communication Workers Union reach an agreement, but recognised the CWU had other issues to resolve.
The Royal Mail and Unite deal consists of a 2.5% increase in base salaries, promotion increases and allowances from April 1 2007 (backdated) to March 31 2008, with further increases of 2% from April 1 2008 and 2.8% from July 1 2008. It also covers bonus arrangements and pay grade changes.
Unite has agreed to support Royal Mail's pension proposals, which call for the final salary scheme to be closed to new members on January 31 2008 and replaced by a defined contribution scheme.