Customers are urging Post Office bosses to make sure experienced staff are not lost when the Blackmore branch moves 50 yards in the village.
A consultation is on-going about plans to move the service from The Green to the Co-Op supermarket.
If the move goes ahead the new shop will be open longer, from 6.30am to 8pm, seven days a week.
Related: Vandals scrub 'Blackmore' from over 20 village signs
But Blackmore resident Judy Woods said: "They must take into account the three girls who work there and know all the OAPs.
"My view is the three girls who have run the post office for years know the business like the back of their hand.
"The know everyone, they are pleasant and everyone is used to them and it would be an absolute sin to change the staff."
A planning application has already been submitted to Brentwood Borough Council proposing to convert the post office into a house.
Related: Bibles and candles dumped at Blackmore traveller site by Hatton Garden guard
Diane Smith added the proposed village shop in Nine Ashes Road would be a better place for the post office.
The application to change a squash court at Blackmore Sports and Social Club into a shop was given the go ahead in February, although funds have yet to be raised for the makeover.
Mrs Smith said: "We would be better off if the post office could go into the new shop.
"Judy's argument is there is not room in the Co-Op.
"I have already responded to the consultation paper that has been put out, arguing it's silly because the decision has already been made."