an email address is a very effective harvesting countermeasure. The processing required to automatically extract text from images is not economically viable for spammers. It is very inconvenient for users, who type the address in manually. Contact forms Email contact forms which send an email but do not reveal the recipient's address avoid publishing an email address in the first place. However, this method prevents users from composing in their preferred email client, limits message content to plain text - and does not automatically leave the user with a record of what they've said in their "sent" mail folder. JavaScript obfuscation JavaScript email obfuscation produces a normal, clickable email link for users while obscuring the address from spiders. In the source code seen by harvesters, the email address is scrambled, encoded, or otherwise obfuscated. While very convenient for most users, it does reduce accessibility, e.g. for text-based browsers and screen readers, or for those not using a JavaScript-enabled browser. HTML obfuscation In HTML, email addresses may be obfuscated in many ways, such as inserting hidden elements within the address or listing parts out of order and using CSS to restore the correct order. Each has the benefit of being transparent to most users, but none support clickable email links and none are accessible to text-based browsers and screen readers. CAPTCHA Requiring users to complete a CAPTCHA before giving out an email address is an effective harvesting countermeasure. A popular solution is the reCAPTCHA Mailhide service. (Note, 12.9.18: Mailhide is no longer supported.) CAN-SPAM Notice To enable prosecution of spammers under the CAN-SPAM Act of 2003, a website operator must post a notice that "the site or service will not give, sell, or otherwise transfer addresses maintained by such website or online service to any other party for the purposes of initiating, or enabling others to initiate, electronic mail messages." Mail Server Monitoring Email servers use a variety of methods to combat directory harvesting attacks, including to refuse to communicate with remote senders that have specified more than one invalid recipient address within a short time, but most such measures carry the risk of legitimate email being disrupted. Spider Traps A spider trap is a part of a website which is a honeypot designed to combat email harvesting spiders. Well-behaved spiders are unaffected, as the website's robots.txt file will warn spiders to stay away from that area—a warning that malicious spiders