Internet security firm PC Tools has contacted users apologising for sending unsolicited email. The Symantec-owned software vendor apologises for mistakenly sending emails telling users their subscriptions to PC Tools products were due to expire. In most cases, the users had no PC Tools software of any description, let alone a licence about to run out. Updated, 3:04pm

In the apology PC Tools says that the emails were sent out 'due to an error with our email system', and offers a free subscription to PC Tools Privacy Guardian by way of an apology. The company also offers users 30 percent off new products.

A PC Tools spokesperson told PC Advisor that the message was sent out as a consequence of a database error, and was received by around 450,000 people, all of whom are non-paying customers of the company. According to the spokersperson, PC Tools has around 12 million names in its email database, so the email was sent out to fewer than 4 percent of its customers.

The full text of the apology email runs thus:

"We made a mistake! Let us make it up to you.

"Due to an error with our email system, you may have recently received an email indicating your product was about to expire, even if you don't currently have a subscription to a PC Tools product.

We sincerely apologise for the inconvenience."

PC Tools was founded in 2003 and has offices in Australia, the USA, UK, Ireland and Ukraine. It develops and distributes internet security and PC optimisation software such as PC Tools Internet Security 2011 and PC Tools Registry Mechanic 2011. Symantec acquired PC Tools in 2008.