tl;dr
Hide email address from bots without using scripts and maintain mailto: functionality. Method must also support screen-readers.
Summary
Email obfuscation without using scripts or contact forms
Email address needs to be completely visible to human viewers and maintain mailto: functionality
Email Address must not be in image form.
Email address must be "completely" hidden from spam-crawlers and spam-bots and any other harvester type
Desired Effect:
No scripts, please. There are no scripts used in the project and I'd like to keep it that way.
Email address is either displayed on the page or can be easily displayed after some sort of user interaction, like opening a modal.
The user can click on on the email address which in turn would trigger the mailto: functionality.
Clicking the email will open the user's email application.
In other words, mailto: functionality must work.
The email address in not visible or not identified as an email address to bots (This includes the page source)
I don't have an inbox that's full of spam
What does NOT Work
Adding a contact form - or anything similar - instead of the email address
I hate contact forms. I rarely fill up a contact form. If there's no email address, I look for a phone number, and if that's not there, I start looking for an alternative service. I would only fill up a contact form if I absolutely have to.
Replacing the address with an image of the address
This creates a HUGE disadvantage to someone using a screenreader (please remember the visually impaired in your future projects)
It also removes the mailto: functionality unless you make the image clickable and then add the mailto: functionality as the href for the link, but that defeats the purpose and now the email is visible to bots.
What might work:
Clever usage of pseudo-elements in CSS
Solutions that make use of base64 encoding
Breaking up the email address and spreading the parts across the document then putting them back together in a modal when the user clicks a button (This will probably involve multiple CSS classes and the usage of anchor tags)
Alterting html attributes via CSS
#MortezaAsadi gracefully brought up the possibility in the comments below. This is the link to the full - The article is from 2012:
What if We Could Use CSS to Alter HTML Attributes?
Other creative solutions that are beyond my scope of knowledge.
Similar Questions / Fixes
JavaScript: Protect your email address by Joe Maller
(This a great fix suggested by Joe Maller, it works well but it's script based. Here's what it looks like;
<SCRIPT TYPE="text/javascript">
emailE = 'example.com'
emailE = ('yourname' + '#' + emailE)
document.write('' + emailE + '')
</script>
<NOSCRIPT>
Email address protected by JavaScript
</NOSCRIPT>
Looking for a PHP only email address obfuscator function
(A Clever solution using both PHP and CSS to first reverse the email using PHP then reverse it back with CSS) A very promising solution that Works great! But it's too easy to solve.
Is it worth obfuscating email addresses on the web these days?
(JavaScript fix)
Best way to obfuscate an e-mail address on a website?
The selected answer works. It actually works really well. It involves encoding the email as html entities. Can it be improved?
Here's what it looks like;
<A HREF="mailto:
yourname#domain.com">
yourname#domain.com
</A>
Does e-mail address obfuscation actually work?
(The selected answer to this SuperUser question is great and it presents a study of the amount of spam received by using different obfuscation methods.
It seems that manipulating the email address with CSS to make it rtl does work. This is the same method used in the first question I linked to in this section.
I am uncertain what effects adding mailto: functionality to the fix would have on the results.
There are also many other questions on SO which all have similar answers. I have not found anything that fits my desired effect
The Question:
Would it be possible to increase the efficiency (ie as little spam as possible) of the email obfuscation methods above by combining two or more of the fixes (or even adding new fixes) while:
A- Maintaining mailto: functionality; and
B- Supporting screen-readers
Many of the answers and comments below pose a very good question while indicating the impossibility of doing this without some sort of js
The question that's asked/implied is:
Why not use js?
The answer is that I am allergic to js
Joking aside though,
The three main reasons I asked this question are:
Contact forms are becoming more and more accepted as a replacement
for providing an email address - which they should not.
If it can be done without scripting then it should be done without
scripting.
Curiosity: (as I am in fact using one of the js fixes currently) I wanted to see if discussing the matter would lead to a better way of doing it.
The issue with your request is specifically the "Supporting screen-readers", as by definition screen readers are a "bot" of some sort. If a screen-reader needs to be able to interpret the email address, then a page-crawler would be able to interpret it as well.
Also, the point of the mailto attribute is to be the standard of how to do email addresses on the web. Asking if there is a second way to do that is sort of asking if there is a second standard.
Doing it through scripts will still have the same issue as once the page is loaded, the script would have been run and the email address rendered in the DOM (unless you populate the email address on click or something). Either way, screen readers will still have issues with this since it's not already loaded.
Honestly, just get an email service with a half decent spam filter and specify a default subject line that is easy for you to sort in your inbox.
Email me
What you're asking for is if the standard has two ways to do something, one for bots and the other for non-bots. The answer is it doesn't, and you have to just fight the bots as best you can.
Defeating email bots is a tough one. You may want to check out the Email Address Harvesting countermeasures section on Wikipedia.
My back-story is that I've written a search bot. It crawled 105,000+ URLs during it's initial run many years ago. From what I've learned from doing that is that web crawling bots literally see EVERYTHING that is text, which appears on a web page. Bots read everything except images.
Spam can't be easily stopped via code for these reasons:
CSS & JS are irrelevant when using the mailto: tag. Bots specifically look at HTML pages for that "mailto:" keyword. Everything from that colon to the next single quote or double quote (whichever comes first) is seen as an email address. HTML entity email addresses - like the example above - can be quickly translated using a reverse ASCII method/function. Running the JavaScript code snippet above, quickly turns the string which starts with: your... into... yourname#example.com. (My search bot threw away hrefs with mailto:email addresses, as I wanted URLs for web pages & not email addresses.)
If a page crashes a bot, the bot author will tune the bot to fix the crash with that page in mind, so that the bot won't crash at that page again in the future. Thus making their bot smarter.
Bot authors can write bots, which generate all known variations of email addresses... without crawling pages & never using any starter email addresses. While it may not be feasible to do that, it's not inconceivable with today's high-core count CPUs (which are hyper-threaded & run at 4+ GHz), plus the availability of using distributed cloud-based computing & even super computers. It's conceivable that someone can now create a bot-farm to spam everyone, without knowing anyone's email address. 20 years ago, that would have been incomprehensible.
Free email providers have had a history of selling their free user accounts to their advertisers. In the past, simply signing up for a free email account automatically guaranteed them a green light to start delivering spam to that email address... without ever using that email address online. I've seen that happen multiple times, with famous company names. (I won't mention any names.)
The mailto: keyword is part of this IETF RFC, where browsers are built to automatically launch the default email clients, from links with that keyword in them. JavaScript has to be used to interrupt that application launching process, when it happens.
I don't think it's possible to stop 100% of spam while using traditional email servers, without using filters on the email server and possibly using images.
There is one alternative... You can also build a chat-like email client, which runs internally on a website. It would be like Facebook's chat client. It's "kind of like email", but not really email. It's simply 1-to-1 instant messaging with an archiving feature... that auto-loads upon login. Since it has document attachment + link features, it works kind of like email... but without the spam. As long as you don't build an externally accessible API, then it's a closed system where people can't send spam into it.
If you're planning to stick with strictly traditional email, then your best bet may be to run something like Apache's SpamAssassin on a company's email server.
You can also try combining multiple strategies as you've listed above, to make it harder for email harvesters to glean email addresses from your web pages. They won't stop 100% of the spam, 100% of the time... while also allowing 100% of the screen readers to work for blind visitors.
You've created a really good starting look at what's wrong with traditional email! Kudos to you for that!
A good screen reader is JAWS from Freedom Scientific. I've used that before to listen to how my webpages are read by blind users. (If you hear a male voice reading both actions [like clicking on a link] & text, try changing 1 voice to female so that 1 voice reads actions & another reads text. That makes it easier to hear how the web page is read for the visually impared.)
Good luck with your Email Address Harvesting countermeasure endeavours!
Here is an approach that does make use of JavaScript, but with a rather small foot-print. It's also very "ghetto", and generally I would not recommend an approach with inline JS in the HTML except you have an extreme reluctance to use JS, at all.
<a
href="#"
data-contact="bGUtZW1haWxAdGhlLWRvbWFpbi5jb20="
data-subj="QW4gQW1hemluZyBTdWJqZWN0"
onfocus="this.href = 'mailto:' + atob(this.dataset.contact) + '?subject=' + atob(this.dataset.subj || '')"
>
Send an email
</a>
data-contact is the base64 encoded email address. And, data-subj is an optional base64 encoded subject.
The main challenge with doing this without JS is that CSS can't alter HTML attributes. (The article you linked is a "pie-in-the-sky" musing and does not have any bearing on what is possible today or in the near future.)
The HTML entities approach you mentioned, or some variation of it, is likely the simplest option that will have some efficacy. Additionally, the iframe approach is clever and the server redirect approach is pretty awesome. But, all three are vulnerable to bots:
The HTML entities just need to be converted (and detecting that is simple)
The document referenced by the iframe might simply be followed
The server redirect might simply be followed, as well
With the approach outlined above, the use of a base64 encoded email address in a data-contact attribute is very "one-off" – as long as the scraper is not specifically designed for your site, it should work.
Simple + Lot of # + Editable without tools
<a href="mailto:user#domain##com"
onmouseover="this.href=this.href.replace('##','.')">
Send email
</a>
Have you considered using google's recaptcha mailhide?
https://www.google.com/recaptcha/admin#mailhide
The idea is that when a user clicks the checkbox (see nocaptcha below), the full e-mail address is displayed.
While recaptcha is traditionally not only hard for screen readers but also humans as well, with the roleout of google's nocaptcha recaptcha which you can read about
here as they relate to accessibility tests. It appears to show promise with to screen readers as it renders as a traditional checkbox from their view.
Example #1 - Not secure but for easy illustration of the idea
Here is some code as an example without using mailhide but implementing something using recaptcha yourself: https://jsfiddle.net/43fad8pf/36/
<div class="container">
<div id="recaptcha"></div>
</div>
<div id="email">
Verify captcha to get e-mail
</div>
function createRecaptcha() {
grecaptcha.render("recaptcha", {sitekey: "6LcgSAMTAAAAACc2C7rc6HB9ZmEX4SyB0bbAJvTG", theme: "light", callback: showEmail});
}
createRecaptcha();
function showEmail() {
// ideally you would do server side verification of the captcha and then the server would return the e-mail
document.getElementById("email").innerHTML = "email#example.com";
}
Note: In my example I have the e-mail in a JavaScript function. Ideally you would have the recaptcha validated on the server end, and return the e-mail, otherwise the bot can simply get it in the code.
Example #2 - Server side validation and returning of e-mail
If we use an example more like this, we get additional security: https://designracy.com/recaptcha-using-ajax-php-and-jquery/
function showEmail() {
/* Check if the captcha is complete */
if ($("#g-recaptcha-response").val()) {
$.ajax({
type: ‘POST’,
url: "verify.php", // The file we’re making the request to
dataType: ‘html’,
async: true,
data: {
captchaResponse: $("#g-recaptcha-response").val() // The generated response from the widget sent as a POST parameter
},
success: function (data) {
alert("everything looks ok. Here is where we would take 'data' which contains the e-mail and put it somewhere in the document");
},
error: function (XMLHttpRequest, textStatus, errorThrown) {
alert("You’re a bot");
}
});
} else {
alert("Please fill the captcha!");
}
});
Where verify.php is:
$captcha = filter_input(INPUT_POST, ‘captchaResponse’); // get the captchaResponse parameter sent from our ajax
/* Check if captcha is filled */
if (!$captcha) {
http_response_code(401); // Return error code if there is no captcha
}
$response = file_get_contents("https://www.google.com/recaptcha/api/siteverify?secret=YOUR-SECRET-KEY-HERE&response=" . $captcha);
if ($response . success == false) {
echo ‘SPAM’;
http_response_code(401); // It’s SPAM! RETURN SOME KIND OF ERROR
} else {
// Everything is ok, should output this in json or something better, but this is an example
echo 'email#example.com';
}
People who write scrapers want to make their scrapers as efficient as possible. Therefore, they won't download styles, scripts, and other external resources. There's no method that I know of to set a mailto link using CSS. In addition, you specifically said you didn't want to set the link using Javascript.
If you think about what other types of resources there are, there's also external documents (i.e. HTML documents using iframes). Almost no scrapers would bother downloading the contents of iframes. Therefore, you can simply do:
index.html:
<iframe src="frame.html" style="height: 1em; width: 100%; border: 0;"></iframe>
frame.html:
My email is me#example.com
To human users, the iframe looks just like normal text. Iframes are inline and transparent by default, so we just need set its border and dimensions. You can't make the size of the iframe match its content's size without using Javascript, so the best we can do is giving it predefined dimensions.
First, I don't think doing anything with CSS will work. All bots (except Google's crawler) simply ignore all styling on websites. Any solution has to work with JS or server-side.
A server-side solution could be making an <a> that links to a new tab, which simply redirects to the desired mailto:
That's all my ideas for now. Hope it helps.
Short answer to fulfill all your requirements is that it's impossible
Some of the script-based options answered here may work for certain bots, but you wanted no-script, so, no, you can't.
based on the code of MaanooAk, here is my version:
<a href="mailto: Mike Myers"
onclick="this.href=this.href.replace(' Mike ','MikeMy'); this.href=this.href.replace('Myers','ers#vwx.yz')">✉ Send Email</a>
The difference to MaanookAks version is, that on hover you don't see mailto: and a broken email adress but mailto: and the name of contact. And when you click on it, the name is replaced by the email adress.
In the code the email adress is splitted into two parts. Nowhere in the code the email adress is visible complete.
Here is my new solution for this. I first build the email adress string by addition of small pieces and then use this string also as title:
adress = 'mailt' + 'o:MikeM' + 'yers#v' + 'wx.yz';
document.getElementsByClassName('Email')[0].title = adress;
function mail(){window.location.href = adress;}
<a class='Email' onclick='mail()'>✉ Send Email</a>
I use this in a footer of a website. Many pages with all the same footer.
PHP solution
function printEmail($email){
$email = ''.$email.'';
$a = str_split($email);
return "<script>document.write('".implode("'+'",$a)."');</script>";
}
Use
echo printEmail('test#example.com');
Result
<script>document.write('<'+'a'+' '+'h'+'r'+'e'+'f'+'='+'"'+'m'+'a'+'i'+'l'+'t'+'o'+':'+'t'+'e'+'s'+'t'+'#'+'g'+'m'+'a'+'i'+'l'+'.'+'c'+'o'+'m'+'"'+'>'+'t'+'e'+'s'+'t'+'#'+'g'+'m'+'a'+'i'+'l'+'.'+'c'+'o'+'m'+'<'+'/'+'a'+'>');</script>
P.S. Requirement: user must have JavaScript enabled
The one method I found effective is using it with CSS like below:
<a href="mailto:myemail#ignore-domain.com">myemail#<span style="display:none;">ignore-</span>example.com
and then write a JavaScript to remove the ignoreme- word from the href="mailto:..." attribute with regex. This will hide email from bot as it will append ignore- word before real domain and this will work on screen reader and when user clicks on the link custom JS function will remove the ignore- word from href attribute so it will open the real email.
This method has been working very effectively for me till date. you can read more on this - http://techblog.tilllate.com/2008/07/20/ten-methods-to-obfuscate-e-mail-addresses-compared/
I have to display my email address on my website and I'm using this format email[at]domain.com for anti-spam purposes, but one of my colleague told me to use this format instead email#domain.com so the visitor could easily copy the address and paste it on the mailer. And I see some website also use image for their email address. So what could be the best way to do it?
email[at]domain.com, email#domain.com or use an image like this :
Thank you.
The correct way? Make it an URI (using the mailto URI scheme) and link it (using the a HTML element).
email#example.com
The best way? Depends on your criteria.
If you want to make the life of your visitors (including humans as well as bots) easier, use a link.
If you want to make the life of your visitors (including humans as well as bots) harder, obfuscate the address.
"Harder" can also mean impossible, depending on the way how you obfuscate. Many blind users will not be able to access your email address if you post it as an image. Some users with intellectual disabilities will not be able to swap [at] with #. Users without copy-paste functionality might not be able to remember your address when switching applications and having to enter it manually. Users without JavaScript might not be able to access some clever widgets. And so on.
There are several ways to show your email details. For advanced thought you could use QR Code also. In the question that you've asked has relevance that the usage of email in the format like wwxx#example.com is taking a risk like the spam bots catch it from the html DOM.
You could use some scripts like this to protect.
<span id="email">email[at]domain.com</span>
<!-- Please enter a valid email address -->
<SCRIPT TYPE="text/javascript">
var emailE='emailserver.com'
var emailE=('yourname' + '#' + emailE)
var emailAttr = document.getElementById("email");
document.getElementById("email").innerHTML ='' + emailE + '';
//-->
</script>
There are also some encoding techniques you could adapt.
We are building a webservice that allows users to send files as attachments to an e-mail-address like 'long hash'#files.example.com
We would like to allow them to add this e-mail-address to their mail-software with a nice name in a simple manner. We have two ideas for how to achieve this:
Send an e-mail to them from the e-mail-address.
Pros: The user don't have to do anything
Cons: It might stick in the spam filter. Not sure if most e-mail-software adds incoming e-mail addresses to the contacts.
Allow the user to click a mailto: link and send an empty mail to the e-mail-address.
Pros: Less risk of lack of support in e-mail software.
Cons: Forcing the user to do something.
Currently we're considering doing both. Does anyone have any knowledge about these approaches or maybe some other suggestion on how to achieve the same effect?
How about a vCard?
You could use a HTML link:
<a href="data:text/vcard,BEGIN:VCARD
VERSION:2.1
N:Last name;First name
FN:Full name
ORG:Me Ltd.
TITLE:vCard Title
PHOTO;GIF:http://www.example.com/photo.gif
EMAIL;PREF;INTERNET:hash#example.com
REV:20140215T212230Z
END:VCARD" download="mycard.vcf">Add us to your mailbook</a>
See http://jsfiddle.net/9jZRz/ for a demo.
I have created an html form with text boxes and radio buttons ect.
I can email the form to an email address.
now the problem, when i fill in the form and click reply, i only get my blank html form back no values were left inside the textbox's.
Please help
We did some fairly extensive research about HTML forms in emails for a client of ours. The bottom line is that it barely works, so it’s best to link to a form in a browser.
What Quentin said holds water, many email clients (cough, outlook) are very specific in regards to their support for HTML emails. In fact most don't even support div's or embedded <style> blocks. Let alone an HTML form.
Your best bet is to use a URL that they click on, which in-turn opens up a form for them to fill out. If you need to capture some of their information automatically (such as email). you can generate query strings and in your mailer have it add the information in dynamicallly..
i.e; <a href="http://awesomeform.com/form.php?email=$client_email">
In email it would look like: http://awesomeform.com/form.php?email=myemail#email.com
Either way
If you are insistent on attempting this, use the email boilerplate to get you started. It has a ton of "best practices" and tips/tricks built right into it.
http://htmlemailboilerplate.com/
Complex HTML doesn't mix with many email clients. Forms are especially poorly supported.
Link to an HTML document available over HTTP instead. People can click a link and open it in a regular web browser.
I'm making a simple RSVP form and I'd for users to click a mailto link, which opens an pre-made email with parts already filled out (first name, etc.) and then send it to RSVP for an event. I know this isn't the best way, but it's the simplest I could come up with.
The only problem is that I can't seem to put character return's in the mailto link, so it looks messy. Any idea how?
My mailto link:
RSVP
Since you are placing your data in a URL, you need to encode such characters using %XX hex notation, eg:
RSVP
FYI, keep in mind that not all email programs support multiple parameters to the mailto: protocol, if any at all. You really should look into using a server-side webform instead. Let your users submit feedback to you directly from your website without invoking their local email program at all. Most website hosting services provide such a feature as part of your account, or for a small fee.