Australian businesses and consumers have been left searching for answers after an Australia Post delivery rival abruptly shut up shop without warning.

Sydney-based Sendle emailed business customers late on Sunday, warning it would halt all pick-up and delivery bookings “effective immediately”.

The decision comes five months after the company merged with two US businesses and 12 years after the start-up launched, promising to challenge Australia Post on parcel deliveries.

The shutdown is expected to hit small businesses the hardest as the company had ties with online providers Shopify and eBay Australia – although consumers awaiting parcels delivered by Sendle may also miss out.

Sendle’s message to customers warned the company would no longer accept parcel delivery bookings from January 12 and existing deliveries may not reach their destinations.

“Any parcels that have already been picked up and are in transit will be delivered at the discretion of the delivery partner,” the message read.

“Any existing bookings scheduled for pick-up on 12 January or later will be cancelled.”

Customers learned of the closure in an email on Sunday.

A banner on Sendle’s Australian website also confirms the closure, and its social media accounts have been disabled.

“So Sendle has gone to the wall. I’m probably one of thousands in wondering if I’ll still get that package I bought via eBay,” one disgruntled customer wrote on X.

“Yeah, any parcels in transit delivered at the discretion of the delivery partner sounds pretty bad. I wonder what’s going to happen to all those parcels?” wrote another.

Another customer said they had “literally booked jobs over the last few days and they’ve all been nuked”.

However, the company provided little detail about the sudden shutdown or what it would mean for its clients.

“Sendle has informed its customers that it is no longer taking any future bookings,” it said.

“We are not able to provide any further comment at this time.”

Sendle’s website confirmed the closure, without providing further information.

Sendle was founded in 2014 as a rival to Australia Post, offering door-to-door deliveries at a lower cost than its competitors’ Parcel or Express Post services.

The company, founded by James Chin Moody, Sean Geoghegan and Craig Davis, signed deals with businesses such as Shopify, eBay Australia, Squarespace and WooCommerce to provide shipping solutions for small traders, and also offered carbon neutral deliveries.

Sendle boss James Chin Moody. Photo: Sendle

In an interview at the time, Moody said the national postal system was “very ripe for disruption” and Australia Post should be forced to work with providers like Sendle to improve the delivery network.

“How does Australia Post serve the national interest?” he said.

“Is it serving it by being a competitor and trying to be a monopoly that we believe is driving up prices, or does it serve it by saying we want to become a platform for a whole ecosystem of delivery?”

In August, Sendle merged with US companies FirstMile and ACI Logistix to form FAST Group serving customers in the US, Australia, Canada, India and the Philippines.

But Sydney investment firm Federation Asset Management – an investor in the merged company – froze redemptions in its fund in December after raising questions about financial statements.

-with AAP