For anyone who needs to put their email address onto a web site there is the constant threat of having that email address being picked up by the automatic email address harvesters employed by spammers and then having the problem of being inundated by unwanted email. The Center for Democracy & Technology have produced a report on where addresses are the most vulnerable and what can be done about it.
The report can (sometimes) be found at:
http://www.cdt.org/speech/spam/030319spamreport.shtml
...however, it seems to no longer be available thought their search page still lists it!
Their main line of counter-attack is to convert the email address into something that the spammers' tools do not (currently) recognise. There tends to be three main approaches of which the report mentions the first two:
- replacing the '.' and '@' characters with ' dot ' and ' at ';
- replacing all characters in the address with the &#nnn; format where nnn is a 3-digit decimal value of the character to be converted;
- converting the whole email address into a graphic.
The following pages show how web sites using the PHP programming language can be used to implement any of these methods.
