The town of Beechworth in Victoria's north-east has just two post boxes for its 3,859 residents.

And for nearly six months, one was completely forgotten, uncleared until a local couple raised the alarm after finding it bursting with mail.

For months, Joanne and Mick Westra, who own a plumbing supplies business in the town, had noticed something strange.

Long-time customers stopped paying their accounts. A wedding RSVP disappeared in the mail, as well as their son's phone.

Their neighbours had also noticed vanishing Christmas cards, birthday cards, even bank cheques.

And in early March, when Mick went to mail a document at their local post box — conveniently located just 10 metres from their shop — he found it wouldn't fit.

'Absolutely chock-a-block'

After returning to discuss his discovery with wife Ms Westra, the penny finally dropped.

"It was full. Absolutely chock-a-block full. And then we started to work it all out," Ms Westra said.

"We were wondering, these are usually really good payers. Why are they overdue? There were just so many of them, that's why we clicked — because they've never received them."

A sign posted in October announced a change in clearing times, but from that date forward the post box hadn't been cleared.

A call to Australia Post resulted in a prompt visit by local Australia Post employee Wendy, who was "horrified" to find two crates full of undelivered mail inside.

More than 200 invoices and other documents from the Westras' business had never travelled more than a few metres from their shop.

Their 19-year-old son had also spent five months fighting a $900 bill for an unreturned phone.

"He had five months worth of grief from them. He is 19, they didn't believe him," Ms Westra said.

Mick and Joanne Westra with their sons, from left to right, Sam, Dyllon and Mitchell. ( Supplied: Joanne Westra )

Postal survey 'close to our hearts'

For Ms Westra, the most upsetting lost mail was the marriage postal survey forms the family had sent in October.

"Three of them from my family were posted in that mailbox and it was never cleared. And that's close to our hearts, because we do have a gay son. And we didn't support him in the postal vote."

Australia Post responded with an apology, returning four months of mail to its senders, and delivering the most recent month's mail with an apologetic letter.

"Australia Post wholeheartedly apologises for the error. We can confirm all the mail has now been delivered with a letter of explanation and apology," an Australia Post spokesperson said.

"This is an isolated incident that occurred when the collection route was handed over to a different team.

"We began clearing the street posting box again three weeks ago."

Ms Westra was told the cause was a change in contracts.

After asking for compensation, Australia Post responded with a $50 mail order voucher and $200 worth of stamps.

Ms Westra said while she wasn't all that satisfied with Australia Post's response, she and Mick would continue to use snail mail because it was important for their business.

"We do also use email. It's about 50-50. Older people and a certain majority of people still prefer to get the hard copy in the post and we don't have a problem with that ... usually," she said.