GreenNet wants to support its members in using email for effective campaigning for political and social change.  Having a mailing list of supporters and online petitions seems to be a good way of building a mass movement, and many GreenNet users have lists of thousands or tens of thousands of members or supporters.  Technically, a mailing list could be administered by one of:
  • using software on our list server (such as Mailman);
  • using mailing list software like PHPList (or a custom system) on a site hosted with us;
  • using us as a "smarthost" for sending email from your own database.

However, there are dangers in running an email list, and not just of encouraging "slacktivism" or "clicktivism".  Technically as well as strategically, you need to take steps to ensure that all addresses on the list want to get the information.  That is, that they have definitely consented to receive bulk email from you or your organisation, and have not since withdrawn that consent. 

One thing to be particularly cautious about is inadvertently signing up addresses which have no connection to the campaign at all.  How can this happen?  Well, wherever there is a form on a website, there is a danger of a "bot" visiting and entering spam text and a random email address being used on the form.  The address that is inadvertently subscribed might be:

  1. the address of someone who is annoyed by your repeated unsolicited emails, who may well report them as spam; or
  2. the address of a "spamtrap".  Spamtraps are a useful method of detecting spam and sharing information about spammers among the internet community.  But if GreenNet gets listed in a spam dirtylist, it will mean that email from other users might bounce or be delayed; as we say in our terms and conditions, we reserve the right to curtail use of services if it endangers the service given to others.

Therefore we ask that you only subscribe an address to a mailing list if there is confirmation of opt-in ("COI").  In many cases you may know people individually or that they have definitely consented to go on a mailing list.  In other cases where you rely on the information supplied through an automated system, it is necessary to think about what is ensuring that subscriptions are only from validated or confirmed addresses. 

Another danger can be that when people who were once interested in the campaign unsubscribe, but you continue to import the list from a database elsewhere.  Here's a quick list of ideas about keeping your list clean:


  • Ask people signing a petition whether they want email updates, and make sure you honour that, tending to omit the address if unsure.
  • Consider a Captcha on any form on the web, provided it is accessible for people with sensory impairments.  Other forms of validation might also filter out the random data supplied by bots, for example if you are asking people for their postcodes (or use Mollom or other anti-spammer services mentioned below).  Try to avoid free-text fields on the same page as the email field as it tends to attract bots - in fact, it may be more effective to ask people to send email individually to a public address with their comments.
  • Consider this at the stage of designing the site.
  • If using Mailman, use the "Confirm" or "Confirm and Approve" options under Privacy Options.  From addresses in ordinary email can also be faked, so if using some other system ensure the owner of the email address has to take some option to confirm their membership.
  • Act on any unsubscribe emails, however received, before the next mailout.
  • Make sure that bounces from your mailing list software are sent somewhere where they are either automatically processed by the mailing list software, or otherwise manually removed (a job for an intern?).  Some bounces, such as those indicating a full mailbox, might be considered temporary and so less important.
  • Get notifications of any requests to unsubscribe through Mailman or other software and apply them to any other database you have.
  • If your site with the sign-up page is not hosted on GreenNet, check your host is running some system (such as mod-security) to keep out spammers, or the site designer is using a service like Akismet, Mollom, a Captcha or the Drupal spambot module (written by GreenNet).



  • Assume that every email address submitted via a website has been submitted by a human being, or by the owner of the address.  (As well as the spambots, there occasionally are purely malicious attempt to subscribe a victim's address to many lists, or the same list many times.)
  • Keep multiple copies of a supporter database without synchronising them.
  • Worry about email addresses being unsubscribed automatically by your mailing list software.  It's meant to do that, for a good reason.  On a list of 1000 email addresses you've just imported, it would not be unreasonable to expect as many as 100 bounces from misspelled or misentered or obsolete address.
  • Ever buy a list of email addresses.  You've no idea where it's been.


If you have problems setting up bounce processing or dealing with requests to unsubscribe, please let us know.  A "dirty" list where you can't tell which email addresses are good and which bad is really not something you want.