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FAQ: How do spammers get people's email addresses ?

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Posting-Frequency: monthly
Copyright: (c) 1999-2004 Uri Raz
Maintainer: Uri Raz <>
Last-modified: 4/Aug/2004
Archive-Name: net-abuse-faq/harvest

See reader questions & answers on this topic! - Help others by sharing your knowledge
 There are many ways in which spammers can get your email address. The
 ones I know of are :

   1. From posts to UseNet with your email address.
      Spammers regularily scan UseNet for email address, using ready made
      programs designed to do so. Some programs just look at articles
      headers which contain email address (From:, Reply-To:, etc), while
      other programs check the articles' bodies, starting with programs
      that look at signatures, through programs that take everything that
      contain a '@' character and attempt to demunge munged email addresses.
      There have been reports of spammers demunging email addresses on
      occasions, ranging from demunging a single address for purposes
      of revenge spamming to automatic methods that try to unmunge email
      addresses that were munged in some common ways, e.g. remove such
      strings as 'nospam' from email addresses.
      As people who where spammed frequently report that spam frequency to
      their mailbox dropped sharply after a period in which they did not
      post to UseNet, as well as evidence to spammers' chase after 'fresh'
      and 'live' addresses, this technique seems to be the primary source
      of email addresses for spammers.
   2. From mailing lists.
      Spammers regularily attempt to get the lists of subscribers to
      mailing lists [some mail servers will give those upon request],
      knowing that the email addresses are unmunged and that only a few
      of the addresses are invalid.

      When mail servers are configured to refuse such requests, another
      trick might be used - spammers might send an email to the mailing
      list with the headers Return-Receipt-To: <email address> or
      X-Confirm-Reading-To: <email address>. Those headers would cause some
      mail transfer agents and reading programs to send email back to
      the <email address> saying that the email was delivered to / read at 
      a given email address, divulging it to spammers. 
      A different technique used by spammers is to request a mailing
      lists server to give him the list of all mailing lists it carries
      (an option implemented by some mailing list servers for the
      convenience of legitimate users), and then send the spam to the
      mailing list's address, leaving the server to do the hard work
      of forwarding a copy to each subscribed email address.
      [I know spammers use this trick from bad experience - some spammer
       used this trick on the list server of the company for which I work,
       easily covering most of the employees, including employees working
       well under a month and whose email addresses would be hard to find
       in other ways.]
   3. From web pages.
      Spammers have programs which spider through web pages, looking for
      email addresses, e.g. email addresses contained in mailto: HTML
      tags [those you can click on and get a mail window opened]

      Some spammers even target their mail based on web pages.
      I've discovered a web page of mine appeared in Yahoo as some spammer
      harvested email addresses from each new page appearing in Yahoo and
      sent me a spam regarding that web page.

      A widely used technique to fight this technique is the 'poison' CGI
      script. The script creates a page with several bogus email addresses
      and a link to itself. Spammers' software visiting the page would
      harvest the bogus email addresses and follow up the link, entering
      an infinite loop polluting their lists with bogus email addresses.

      For more information about the poision script, see
   4. From various web and paper forms.

      Some sites request various details via forms, e.g. guest books &
      registrations forms. Spammers can get email addresses from those
      either because the form becomes available on the world wide web,
      or because the site sells / gives the emails list to others.

      Some companies would sell / give email lists filled in on paper
      forms, e.g. organizers of conventions would make a list of
      participants' email addresses, and sell it when it's no longer needed.

      Some spammers would actually type E-mail addresses from printed 
      material, e.g.  professional directories & conference proceedings.

      Domain name registration forms are a favourite as well - addresses are
      most usually correct and updated, and people read the emails sent to
      them expecting important messages.

   5. Via an Ident daemon.
      Many unix computers run a daemon (a program which runs in the 
      background, initiated by the system administrator), intended to
      allow other computers to identify people who connect to them.
      When a person surfs from such a computer connects to a web site
      or news server, the site or server can connect the person's computer
      back and ask that daemon's for the person's email address.
      Some chat clients on PCs behave similarily, so using IRC can cause
      an email address to be given out to spammers.

   6. From a web browser.
      Some sites use various tricks to extract a surfer's email address
      from the web browser, sometimes without the surfer noticing it.
      Those techniques include :
       1. Making the browser fetch one of the page's images through an
          anonymous FTP connection to the site.
           Some browsers would give the email address the user has 
           configured into the browser as the password for the anonymous
           FTP account. A surfer not aware of this technique will not
           notice that the email address has leaked.
       2. Using JavaScript to make the browser send an email to a chosen
          email address with the email address configured into the browser.
           Some browsers would allow email to be sent when the mouse 
           passes over some part of a page. Unless the browser is properly
           configured, no warning will be issued.
       3. Using the HTTP_FROM header that browsers send to the server.
           Some browsers pass a header with your email address to every web
           server you visit. To check if your browser simply gives your
           email address to everybody this way, visit

      It's worth noting here that when one reads E-mail with a browser
      (or any mail reader that understands HTML), the reader should be
      aware of active content (Java applets, Javascript, VB, etc) as 
      well as web bugs.

      An E-mail containing HTML may contain a script that upon being
      read (or even the subject being highlighted) automatically sends
      E-mail to any E-mail addresses. A good example of this case is the
      Melissa virus. Such a script could send the spammer not only the 
      reader's E-mail address but all the addresses on the reader's
      address book.

      A web bugs FAQ by Richard M. Smith can be read at
   7. From IRC and chat rooms.
      Some IRC clients will give a user's email address to anyone who cares
      to ask it. Many spammers harvest email addresses from IRC, knowing that
      those are 'live' addresses and send spam to those email addresses.
      This method is used beside the annoying IRCbots that send messages
      interactively to IRC and chat rooms without attempting to recognize
      who is participating in the first place.
      This is another major source of email addresses for spammers, especially
      as this is one of the first public activities newbies join, making it
      easy for spammers to harvest 'fresh' addresses of people who might have
      very little experience dealing with spam.
      AOL chat rooms are the most popular of those - according to reports
      there's a utility that can get the screen names of participants in
      AOL chat rooms. The utility is reported to be specialized for AOL due 
      to two main reasons - AOL makes the list of the actively participating
      users' screen names available and AOL users are considered prime
      targets by spammers due to the reputation of AOL as being the ISP of
      choice by newbies. 
   8. From finger daemons.

      Some finger daemons are set to be very friendly - a finger query
      asking for john@host will produce list info including login names
      for all people named John on that host. A query for @host will
      produce a list of all currently logged-on users.

      Spammers use this information to get extensive users list from hosts,
      and of active accounts - ones which are 'live' and will read their 
      mail soon enough to be really attractive spam targets.

   9. AOL profiles.
      Spammers harvest AOL names from user profiles lists, as it allows them
      to 'target' their mailing lists. Also, AOL has a name being the choice 
      ISP of newbies, who might not know how to recognize scams or know how 
      to handle spam.

  10. From domain contact points.

      Every domain has one to three contact points - administration,
      technical, and billing. The contact point includes the email
      address of the contact person.

      As the contact points are freely available, e.g. using the 'whois'
      command, spammers harvest the email addresses from the contact points
      for lists of domains (the list of domain is usually made available to
      the public by the domain registries). This is a tempting methods for
      spammers, as those email addresses are most usually valid and mail
      sent to it is being read regularily.

  11. By guessing & cleaning.
      Some spammers guess email addresses, send a test message (or a real
      spam) to a list which includes the guessed addresses. Then they
      wait for either an error message to return by email, indicating that
      the email address is correct, or for a confirmation. A confirmation
      could be solicited by inserting non-standard but commonly used
      mail headers requesting that the delivery system and/or mail client
      send a confirmation of delivery or reading. No news are, of coures,
      good news for the spammer.
      Specifically, the headers are -
       Return-Receipt-To: <email-address>      Send a delivery confirmation
       X-Confirm-Reading-To: <email-address>   Send a reading confirmation
      Another method of confirming valid email addresses is sending HTML
      in the email's body (that is sending a web page as the email's content),
      and embedding in the HTML an image. Mail clients that decode HTML,
      e.g. as Outlook and Eudora do in the preview pane, will attempt fetching
      the image - and some spammers put the recipient's email address in the
      image's URL, and check the web server's log for the email addresses of
      recipients who viewed the spam.

      So it's good advice to set the mail client to *not* preview rich media
      emails, which would protect the recipient from both accidently confirming
      their email addresses to spammers and viruses.

      Guessing could be done based on the fact that email addresses are
      based on people's names, usually in commonly used ways
      (first.last@domain or an initial of one name followed / preceded by
      the other @domain)

      Also, some email addresses are standard - postmaster is mandated by
      the RFCs for internet mail. Other common email addresses are
      postmaster, hostmaster, root [for unix hosts], etc.
  12. From white & yellow pages.

      There are various sites that serve as white pages, sometimes named
      people finders web sites. Yellow pages now have an email directory
      on the web.

      Those white/yellow pages contain addresses from various sources,
      e.g. from UseNet, but sometimes your E-mail address will be 
      registered for you. Example - HotMail will add E-mail addresses to
      BigFoot by default, making new addresses available to the public.

      Spammers go through those directories in order to get email addresses.
      Most directories prohibit email address harvesting by spammers, but as
      those databases have a large databases of email addresses + names,
      it's a tempting target for spammers.

  13. By having access to the same computer.

      If a spammer has an access to a computer, he can usually get a list
      of valid usernames (and therefore email addresses) on that computer.

      On unix computers the users file (/etc/passwd) is commonly world
      readable, and the list of currently logged-in users is listed via 
      the 'who' command.

  14. From a previous owner of the email address.

      An email address might have been owned by someone else, who disposed
      of it. This might happen with dialup usernames at ISPs - somebody
      signs up for an ISP, has his/her email address harvested by spammers,
      and cancel the account. When somebody else signs up with the same ISP
      with the same username, spammers already know of it.

      Similar things can happen with AOL screen names - somebody uses a
      screen name, gets tired of it, releases it. Later on somebody else
      might take the same screen name.

  15. Using social engineering.

      This method means the spammer uses a hoax to convince people
      into giving him valid E-mail addresses.

      A good example is Richard Douche's "Free CD's" chain letter.
      The letter promises a free CD for every person to whom the letter is
      forwarded to as long as it is CC'ed to Richard.

      Richard claimed to be associated with Amazon and Music blvd, among
      other companies, who authorized him to make this offer. Yet he
      supplied no references to web pages and used a free E-mail address.

      All Richard wanted was to get people to send him valid E-mail addresses
      in order to build a list of addresses to spam and/or sell.

  16. Buying lists from others.

      This one covers two types of trades. The first type consists of buying
      a list of email addresses (often on CD) that were harvested via other
      methods, e.g. someone harvesting email addresses from UseNet and sells
      the list either to a company that wishes to advertise via email
      (sometimes passing off the list as that of people who opted-in for
      emailed advertisements) or to others who resell the list.

      The second type consists of a company who got the email addresses
      legitimately (e.g. a magazine that asks subscribers for their email
      in order to keep in touch over the Internet) and sells the list for
      the extra income. This extends to selling of email addresses a
      company got via other means, e.g. people who just emailed the company
      with inquiries in any context.

      The third type consist of technical staff selling the email address for
      money to spammers. There was a news story about an AOL employee who
      sold AOL email addresses to a spammer -,39020375,39158500,00.htm

  17. By hacking into sites.

      I've heard rumours that sites that supply free email addresses
      were hacked in order to get the list of email addresses, somewhat
      like e-commerce sites being hacked to get a list of credit cards.

 If your address was harvested and you get spammed, the following pages
 could assist you in tracking the spammer down :

  1. MindSpring's page explaining how to get an email's headers

  2. The spam FAQ, maintained by Ken Hollis.

  3. The Reporting Spam page, an excellent resource.

  4. Reading Mail headers.

  5. Julian Haight's Spam Cop page.

  6. Chris Hibbert's Junk Mail FAQ.

  7. UXN Spam Combat page.

  8. Sam Spade, Spam hunter.

  9. Penn's Page of Spam.

  A. WD Baseley's Address Munging FAQ
  B. Fight Spam on the Internet site

  C. The Spam Recycling Center

  W. The Junk Busters Site

  X. The Junk Email site

  Y. BCP 30: Anti-Spam Recommendations for SMTP MTAs 

  Z. FYI 28: Netiquette Guidelines

     FYI 35: DON'T SPEW 
             A Set of Guidelines for Mass Unsolicited Mailings and Postings

 Several sites on the web will help in tracing spam :

  1. Sam Bretheim's list of traceroute gateways
     To find traceroute gateways in any country, visit here.

  2. gates to whois on any domain world-wide 

  3. A list of whois servers, collected by Matt Power

  4. site - links to NICs worldwide.
     A similar page can be found at

  5. The Coalition Against Usolicited Commerical E-mail.
     The European CAUCE.
     The Coalition Against Unsolicited Bulk Email, Australia.
     The Russian Anti-Spam organization.

  Y. No More Spam - ISP Spam-Blocking Interferes With Business

  Z. Removing the Spam
      By Geoff Mulligan
      Published by O'Reilly
      ISBN 0-201-37957-0
       A good book about handling spam.

 Legal resources :

  1. FTC Consumer Alert - 
      FTC Names Its Dirty Dozen: 12 Scams Most Likely to Arrive Via Bulk email

  2. Report to the Federal Trade Commision of the Ad-Hoc Working Group
     on Unsolicited Commercial Mail.

  3. Pyramid Schemes, Ponzi Schemes, and Related Frauds

  4. The AOL vs. Cyberpromo case

     The AOL vs. the Christian Brothers (the apricot seeds as a cancer
     cure spammers) case.

  5. "Intel scores in email suit", by Jim Hu, CNET,4,29574,00.html?

  6. The John Marshall Law School spam page

  7. First amendment issues related to UBE, by Paul L. Schmehl.
  8. Hawaii's Anti-Spam Law

  9. Washington's Anti-Spam Law

     Also see the WA State Resident site

     A news story about a relevant court case can be found at

  A. California's Anti-Spam Law

  B. Virginia's Anti-Spam Law

  C. Nevada's Anti-Spam Law

  D. The UK Data Protection Law

  E. The Italian Anti-Spam Law

  F. The Austrian Telecm Law

  G. The Norwegian Marketing Control Act

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