Stephen Bates walks almost four miles a day, he works out of the back of a Dodge Caravan, he loves his job and his customers love him.?He?s the greatest. He makes an extra effort – I never get the wrong mail,” said Hamilton Avenue resident David Doyle.Bates has delivered mail out of the main post office on Willow Street for 12 years, working Route 54 in the Highlands for the last three years. He sorts and delivers mail from 8 a.m. to 4:30 p.m., sometimes six days a week, and his route takes him up hilly Highlands streets and staircases through – as the saying goes – rain, sleet and snow, sweltering weather and days when the wind blows.?I like working outside. In the hotter weather, you can always adjust clothing-wise. Winter is tougher – you have to add layers and, if it?s raining, you almost have to pretend it isn?t and just keep working,” he said.The 42-year-old Lynn resident and Lynn Vocational Technical Institute graduate said the independence and self-reliance that defines the successful letter carrier drew him to work for the Postal Service.His day starts in the main post office?s big sorting room where Bates and 30 other letter carriers “case” their mail, moving from one sorting station to another picking up packages, letters and magazines for delivery on their routes.By 9 a.m., Bates has all of his mail organized in the back of his delivery van, where he also keeps tools of the postal trade, including a pith helmet to repel the sun and chemical repellent to ward off the dogs.He delivers, on average, 1,500 letters and 70 to 100 packages a day. Once October arrives, those numbers increase and keep rising as Christmas draws near.?It doesn?t taper off – with returns – until February,” he said.The convenience provided by online shopping has changed Bates? job over the course of his career, with more packages finding their way into his van and ultimately the mailboxes along his route. He uses a hand-held tracking computer to log in delivery times and even the precise location at an address where he leaves a package.?If someone signs up for email alerts, they can find out exactly when and where mail is delivered,” he said.Years spent walking mail routes has made Bates the eyes and ears of the neighborhoods he serves. If mail piles up at a certain address, he?ll check with the resident and invariably learns someone has been ill or on an extended trip.In return, people living along his route offer him bottled water, holiday greetings and even a slice of apple pie at Thanksgiving.?They get to know you and they get to know your schedule and look forward to seeing you,” he said.