The deal, which was reached in April after 18 strike dates, has won 67% of the union’s vote.
Staff will get a 10% pay rise over three years and a one-off lump sum of £500.
In return, Royal Mail won concessions including new seasonal working patterns, later starting times and regular Sunday working.
There will also be an independent inquiry into suspended or sacked workers and reduced use of agency workers, as sought by the CWU.
More about industrial action:
One of the CWU’s main grievances was Royal Mail’s modernisation plans to move to a gig economy-style parcel courier model.
The union said this would erode workers’ rights and rely on casual labour.
Nathan Clements, chief people officer at food service company SSP Group, said the dispute served as a reminder of the importance of communication.
Speaking to HR magazine, he said: “[The Royal Mail] appears to have failed to establish the case for change in ways of working and the need for modernisation in the face of significant competition.
“The learnings are clear: HR teams need to communicate the case for continued change and improvement, whilst keeping up with market rates and their competition on pay.”
Several professions have gone on strike in the past year, including teachers, junior doctors, rail workers, nurses, passport office staff and civil servants.
The government has responded with the Strikes (Minimum Service Levels) Bill, which proposes to mandate a minimum level of service during industrial action from public services, with unions being sued if they fail to comply.
The bill is reaching its final stages, with the consideration of Lords message due to occur next week (17 July).
In order to rebuild employee relations following strikes, and prevent further disputes, Clements said HR teams need to ensure any remaining frustration is dealt with."
“Once the relationship is ‘broken’ there needs to be a reset, refresh and a coming together after the dispute is resolved,” he said.
“Neither side will walk away with all of their wishes.
“This is where frustrations and future grievances will grow, unless tackled head on and quickly as part of the healing process.
“This should be done with all colleagues, not just via the unions or those with union membership.”
He said employers should try and maintain direct communication with their employees.
He added: “Often companies give up the right to talk with all colleagues and use unions as their one communication channel.
"In my experience they are no better than a typical manager at getting their message across.
“It is really important that a company owns direct communications. This can be done in partnership with third parties as needed.”