Attachments in Proprietary Formats Considered Harmful

There are a couple of very good reasons why you should think twice before sending email attachments in proprietary formats, such as the MS-Word document format.

  • It is very easy to spread computer viruses with todays overly complex document formats. You may think that your computer is free of viruses, but consider that by sending documents in, say, the MS-Word format to others, you implicitly invite them to do the same. Do you know whether their computer is virus-free?
  • You may inadvertently transmit some of your own secrets. Many users of MS-Word don't realise that these documents contain all kinds of information that is not displayed when you view it in Word. This includes text of earlier revisions, which you may believe that you deleted, but which is still saved and transmitted as part of a document. This text may be recovered by recipients of a document and may prove to be rather embarrassing.
  • Many proprietary document formats are bloated. Have you ever had a look at how much memory your average MS-Word document consumes? Not too bad given todays hard disk sizes you may think, but consider what happens if you send an email with such a document as an attachment to a list of recipients or even a mailing list. The email, including the attachment, is copied multiple times and if many of the recipients are hosted on the same mail server, the message can put a significant strain on the system.
  • Users of alternative software cannot read your attachments. Proprietary document formats are kept secret by the companies developing them, in an attempt to reduce competition, and thus, choice for the end user. As a consequence, users of alternative software will not be able to read your attachments. In particular, a growing number of computer users rely on alternative operating systems (e.g., current estimates put the number of Linux users at 18 million), which put a strong emphasis on international standards and often reject formats that stifle competition and interoperability; these systems are particularly popular among computer-savvy expert users who you often find at universities, and especially, computing schools.
  • You force others into an upgrade cycle. You may use a newer version of some proprietary software than some of the recipients of your message. Some software vendors make sure to change the document formats with every version in an attempt to force any person that you communicate with to purchase the updated version, too. Do you really want to support this practice?

What is the Alternative?

There are open standards that provide an excellent alternative to proprietary document formats.

  • Plain ASCII text: Unless you need special formatting, good old plain ASCII text is your friend. It can't carry viruses, is space efficient and everybody can read it. ASCII is not only good for plain text, any decent spreadsheet can read and write tables in tab-delimited ASCII format.
  • HTML: The HTML format used in web pages has been standardised by an international standardisation organisation. If you avoid inline code, such as JavaScript, HTML doesn't carry viruses, it is reasonably compact, and can be read on virtually any platform.
  • PostScript and PDF: If you need high quality formatted documents, you may have to resort to either PostScript or PDF. Both formats are well enough standardised to have broad support on most computing platforms. Unfortunately, they do carry a (very much reduced) risk for viruses and can lead to rather large documents, too. A definite plus of these formats over the Word format is that they much more reliably lead to consistent high quality printouts on systems that are configured different to yours. They can also be used to display slides, such as those created by Powerpoint, and also spreadsheets. Unfortunately, the portability of PDF documents is sometimes insufficient and documents cannot be displayed by all PDF previewers (even Adobe's own software fails on some documents).
  • RTF: In cases, where it is necessary for two parties to edit the same document (as opposed to exchange documents for the sole purpose of viewing and printing the documents), the RTF format seems to be the only half-way portable option for WYSIWIG word processors. However, as programs like Word tend to use their own extensions to this format, compatibility is often limited.

A last word regarding large attachments: Do not add large attachments to unsolicited email and messages to mailing lists or newsgroups. There is a good chance that you annoy a significant proportion of the recipients. Instead, ask people to either reply to you and ask for the attachments, or put them on a web site and include a link into your message; then, interested parties can simply download the data.


Copyright [2002..2005] Manuel M T Chakravarty. Unlimited permission to copy, modify, and re-distribute this web page is granted. If you do use material from this web page, I would appreciate a suitable acknowledgement in the derived work.

• Copyright 2005 Manuel M T Chakravarty • Last modified: Tue Apr 19 18:31:27 EST 2005