The controversial new distribution site would see new storage facilities and a vehicle maintenance facility built on land in Patcham Court Farm.
If approved, the current sorting offices in North Road and Denmark Villas would be demolished and replaced with housing.
Campaigners from Patcham Against Royal Mail argue the plans will threaten a conversation and heritage site, increase both traffic and pollution in Patcham, and change a residential area to an industrial one.
Residents will protest outside the site tomorrow afternoon at 2pm and are expected to hang up plastic skeletons, signifying the “grave risks” the planned development poses to the health and wellbeing of the city.
Among those objecting to the plans is Caroline Lucas, MP for the area, who has expressed worries about the “disproportionate impact” that the development will have on residents near the site.
She said: “I cannot in good faith support this proposal and stand fully behind Patcham residents in objecting to its development.”
Conservative group leader Alistair McNair, who represents Patcham on the city council, has also expressed his opposition to the proposal, describing the plan as a “disaster”.
He said: “A sorting office will mean a large-scale business development in a residential area. It will mean HGV lorries coming off the A27 day and night into a narrow residential street. It will mean gridlock on the A27 every rush hour. It will mean postal vans and staff cars parking all over the ward.”
A decision on the proposal, which will be made by the council’s planning committee, is not expected before the autumn.
Comments and objections can be made on the council’s website.