The website crash suffered by Net-a-Porter spin-off The Outnet last week shows that even internet-savvy businesses can get things very wrong.

On Friday, discount high fashion site The Outnet hosted a “pop-up Sale”, offering lots of designer goodies for just a £1. At first glance it could be easy to see how the site could have been deluged with customers far beyond its expectations.

But customers had to register in advance of the Sale going live, so The Outnet will have had good visibility of the numbers it should have expected to try and log on to bag a bargain.

The problem appears to be because it did not plan for everyone who was registered for the Sale trying to log on and buy something at the same time.

In a message to customers that was posted up on Facebook on Monday, The Outnet director Stephanie Phair apologised for the frustration many customers experienced.

She wrote: ‘Clearly, while we were prepared for the volume of traffic the sale would deliver, in some markets, the UK mainly, we were overwhelmed by the speed at which you came to the site this morning. This remarkable volume – up to nine orders a second – led the site to crash for many of you, and I want to say that we are very sorry to all those who didn’t get to buy anything at the sale.’

The Outnet has also promised to take on board the many comments it received on its customer service, so it can provide a better shopping experience in the future.

If a luxury retailer had planned a similar Sale at one of its stores, offering goods at nominal prices, it would have expected to be doing some major crowd control. Yet when something similar is tried on the web, still there persists this myth that because your customers are sat at their desk or at a computer at home that they are not in a queue.

In reality, any time a site experiences high traffic volumes, and especially high levels of customers trying to transact simultaneously, then there will be at least a slowdown in service, if not a complete failure.

Just because you can’t see your online customers pushing and shoving to get through your doors, doesn’t mean they are any less frustrated by a poorly managed event than if they had come to your store in person.