Address munging

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Address munging is the practice of disguising, or munging, an e-mail address to prevent it being automatically collected and used as a target for people and organizations who send unsolicited bulk e-mail. Address munging is intended to disguise an e-mail address in a way that prevents computer software seeing the real address, or even any address at all, but still allows a human reader to reconstruct the original and contact the author: an email address such as, "", becomes "no-one at example dot com", for instance. Any e-mail address posted in public is likely to be automatically collected by computer software used by bulk emailers — a process known as e-mail address harvesting — and addresses posted on webpages, Usenet or chat rooms are particularly vulnerable to this.[1] Private e-mail sent between individuals is highly unlikely to be collected, but e-mail sent to a mailing list that is archived and made available via the web or passed onto a Usenet news server and made public, may eventually be scanned and collected.


Disguising addresses makes it more difficult for people to send e-mail to each other. Many see it as an attempt to fix a symptom rather than solving the real problem of e-mail spam, at the expense of causing problems for innocent users.[2]

The use of address munging on Usenet is contrary to the recommendations of RFC 1036 governing the format of Usenet posts, which requires a valid e-mail address be supplied in the From: field of the post. In practice, few people follow this so strictly.[3]

Disguising e-mail address in a systematic manner (for example, user[at]domain[dot]com), is just as bad as not disguising the address at all as such addresses can be revealed through a simple Google Search.

Any impediment reduces the users willing to take the extra trouble to email the user. In contrast, well maintained email filtering on the user's end does not drive away potential correspondents. Then again, no spam filter is 100% immune to false positives, and the same potential correspondent that would have been deterred by address munging may instead end up wasting time on long letters that will merely disappear in junk mail folders.

For commercial entities, maintaining contact forms on web pages rather than publicizing Email addresses may be one way to ensure that incoming messages are relatively spam-free yet do not get lost. In conjunction with CAPTCHA fields, spam on such comment fields can be reduced to effectively zero, except that non-accessibility of CAPTCHAs bring exactly the same deterrent problems as address munging itself.


As an alternative to address munging, there are several "transparent" techniques that allow people to post a valid e-mail address, but still make it difficult for automated recognition and collection of the address:

An example of munging "" via client-side scripting would be:

<script type="text/javascript">
var name = 'user';
var at = '@';
var domain = '';
document.write(name + at + domain);

The use of images and scripts for address obfuscation can cause problems for people using screenreaders and users with disabilities, and ignores users of text browsers like lynx and w3m, although being transparent means they don't disadvantage non-English speakers that cannot understand the plain text bound to a single language that is part of non-transparent munged addresses or instructions that accompany them.

According to a 2003 study by the Center for Democracy and Technology, even the simplest "transparent name mangling" of e-mail addresses can be effective.[10]


Common methods of disguising addresses include:

Disguised address Recovering the original address
no-one at example (dot) com Replace " at " with "@", and " (dot) " with "." Reverse domain name: elpmaxe to example
remove .invalid
moc.elpmaxe@eno-on Reverse the entire address Instructions in the address itself;
remove .invalid Remove NOSPAM from the address, remove .invalid.
n o - o n e @ e x a m p l e . c o m This is still readable, but the spaces between letters stop automatic spambots.
no-one<i>@</i>example<i>.</i>com (as HTML) This is still readable and can be copied directly from webpages,
but stops many email harvesters.

The reserved top level domain .invalid is appended to ensure that a real e-mail address is not inadvertently generated. One problem is that some spammers will now remove obvious munges and send spam to the cleaned up address.[citation needed] For this reason many people recommend using a totally invalid address[vague] (especially in the From line) and perhaps a disposable email address in the Reply To.


  1. Email Address Harvesting: How Spammers Reap What You Sow, Federal Trade Commission. URL accessed on 24 April 2006.
  2. Address Munging Considered Harmful, Matt Curtin
  3. See Usenet.
  4. Address munging tool(Generator requires the Java Virtual Machine installed and its browser plugin enabled.)
  5. E-mail as an image
  6. Email CSS obfuscation tool (Generator requires javascript enabled, output for displaying emails requires basic CSS)
  7. PHP jumbler tool
  8. JavaScript address script generator (Generator requires cookies enabled, output for displaying emails requires javascript enabled)
  9. PHP contact form generator
  10. "Why Am I Getting All This Spam? Unsolicited Commercial E-mail Research Six Month Report" March 2003.

See also

External links

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