PDF software company Amyuni Technologies has come up with a way for companies to distribute PDF documents without the risk that they will fall foul of spam filters or simply never be read.

The company has launched a new service, PDF Courier, which can be used to deliver PDFs of any size in a secure way with guaranteed delivery. The part that will appeal to companies that depend on this document format, is the word ‘guaranteed'.

The service - which can be web-based, use an Outlook plug-in, or work as a standalone application - solves the issue of a document's fate by offering online tracking, complete with full time stamp verification.

"With the huge increase in spam, many emails and documents never make it to their intended destinations, either because they were blocked or recipients deliberately overlooked them," said Amyuni CTO, Dany Amiouny. "Many read-receipt functionalities included in email applications are simply ignored by recipients, leaving the sender guessing as to whether their important documents were ever read."

Recipients need no special software to receive the PDFs, which turn up in the form of a web link. Interacting with this allows the service to pass back delivery status information to the sender.

PDF Courier also builds in features found on the company's standalone software, such as PDF compression, automatic conversion, and the ability to send file sizes above those allowed by most ISPs.

Although some of what is being offered by Amyuni's PDF Courier expands on convenience issues that have existed since the earliest days of email and the PDF format's popularity, the issue of spam filtering has become a major one since criminals started exploiting attached files to bypass filters.

The problems when spammers started sending large numbers of PDF-based attachments started to become more acute around two years ago containing image spam. At the time, few filters picked up on the technique.

By this year, worries had moved on to criminals actively exploiting flaws in the Acrobat reader to compromise security.

PDF Courier is available in three pricing options, which vary from $49 (£30) to $99 per user, per year.