Ian Wright, who lives in Melton Road, Woodbridge, said letters had been arriving at his home as much as 17 days later.
On one occasion mail about an knee operation arrived late, resulting in him having to change the appointment.
He was also concerned for the welfare of older residents in the area, many of whom relied on the postal service.
READ MORE: Suffolk MP calls for clarity over Boxford Post Office
Mr Wright, who has lived in Melton Road for 17 years, said the service provided by Royal Mail had been “perfect” until May.
“I don’t think it is fair that we pay for the Royal Mail and they treat us this badly.
“I think it could be quite serious, especially as there are a lot of aged people in this area and without your mail and missing appointments, it could be quite serious,” he added.
He said he was lucky that he did not have to rely on the post for bank and credit card statements, adding that he did not know how the Royal Mail would cope during the busy Christmas period.
Mr Wright said he had spoken to neighbours who had also reported receiving “intermittent post”.
READ MORE: Ingham Post Office could become home in plans before council
READ MORE: Woodbridge news
A Royal Mail spokesperson said: “We are committed to delivering mail consistently and on time.
“On occasion, the delivery of mail can be disrupted due to local issues such as staffing or a period of high sick absence at the delivery office.
“In these instances, we work hard to minimise delays and return the service to normal as soon as possible.
“We will investigate this customer’s route to help and ensure any issues impacting their deliveries are resolved.”