Thousands of customers' emails, totalling around 700GB of data, have been lost forever, Internet service provider PlusNet has admitted.
The ISP has apologised profusely for the disaster, which happened in July, and has promised to implement a new platform with "vastly scalable, site resilient mail storage set-up".
The incident has been "taken very seriously within PlusNet", a spokesperson told ZDNet UK on Friday, adding the company's "sincerest apologies for the inconvenience caused by the loss of any customer emails and in particular the unread emails".
PlusNet estimates that half of the missing emails were spam, while only one to two percent of the remaining emails were unread at the time of their deletion.
The disaster was primarily caused by human error: an engineer mistook a live server for a backup server and mistakenly deleted the wrong one.
According to a statement PlusNet released to its customers, that error was compounded when the engineer "attempted to recover the data by creating a volume of the same size in the same place as the first volume... by creating a new volume, the existing inodes [disk indices] were wiped and all data that was on that volume was essentially gone".
The situation was even further exacerbated because the server in question — supplied by Sun after their acquisition of StorageTek — was using a proprietary OS and customised filing system. This forced data recovery specialists to heavily tweak their analysis and recovery software, thus delaying the recovery process.
In the absence of a usable index for the data, PlusNet eventually decided it would be safer to retrieve the server from the data recovery experts, rather than risk further capacity issues.
PlusNet has promised its customers that "an extensive analysis of how this happened has been carried out and working practices implemented to prevent it happening again".
The company has however reiterated its standpoint that "in line with the ISP industry we will not be offering compensation due to a break in service".
ZDNet UK's Jonathan Bennett contributed to this report.