E-mail munging is the anti-spam practice of obfuscating open E-mail addresses in web pages, replacing them by the analogous sequences of HTML entities.
For instance, firstname.lastname@example.org can be munged into
ultrast udio@me ska.inf o
This obfucated sequence, if inserted into HTML, will make browser to render the original E-mail address, and it would be possible to copy-paste it into the mail client address area. However the HTML source code, as visible by the E-mail haveresting spam bot, would contain the munged sequence.
Other texts or even complete articles can also be munged with purpose of making them invisible by search bots, for instance, if it is not desirable to extract that page by search. Unlike robots.txt and meta tags, this method does not require to have access to the server engine.
While it has been argued that it would be easy to program a spam robot to re-convert encodings into text again, most of the spam bots do not do this. Complexity of programming is only part of the problem; handling entities makes the bot slower so it collects less addresses during the same time. As long as there are enough unmasked addresses and munging is not very frequent, this does not make sense.
The study, described in , placed both munged and open E-mail addresses on the web page. These addresses were not used for normal communication, so they only collected spam. While several messages also arrived to the munged addresses, the open addresses collected much more spam. Hence while this method does not provide absolute protection, it can be used to reduce the expected spam amount.