Anyone sending bulk mailings on behalf of an organisation is going to fall foul of spam filters and email firewalls at some point. This article is based on a presentation given at the November 2016 User Network day, where we looked at how spam filters work and how to build mailings taking them into consideration. Generally speaking a spam filter is used by an email service provider to evaluate if an incoming message is spam. Email firewalls are used by organizations or individuals and do the same job at a network or computer level.

Internet definition of spam

Spam filters and email firewalls work in a similar fashion so for simplicity's sake I'll generally use the phrase spam filter in this post. Incoming messages are given a  score based on different criteria (including but not limited to: address sender details, message configuration and the message content). Once your score reaches a certain threshold, your message is marked as spam

As a mail recipient, some messages (badly configured messages or those from addresses or domains blacklisted by spam filters) are blocked before they reach your inbox. Messages that are considered to be possible spam, are downloaded into a separate junk mail folder rather than directly to your inbox.

As a mail sender, you have no way of knowing if your message is being blocked by a spam filter. And the only way you’ll know if your message ends up in the junk folder is if someone tells you.

Am I sending spam?

All spam filters use different criteria, and will score similar content differently. And the list of what may be considered spam changes over time, as spam mailers keep trying to get through the filters. Spam filters also learn from user behavior. So if messages from a particular sender are frequently labelled as junk, or moved to the junk folder by recipients. Future messages from that sender are likely to be considered spam as well.

In short, the likelihood is that someone somewhere is marking your last message as spam

What can I do?

There are a number of things you can do to avoid being caught by spam filters. Firstly there is the content of the mailing itself.

Don’t Click here

Hyperlink text should give the reader a clear idea of the site or page they are clicking through to. Just labelling a hyperlink with the words "click here" doesn’t reflect the content at the other end of the link and could be used to take the recipient anywhere. Use hyperlink text to describe where the reader is about to be taken

  • “see our list of upcoming training courses”
  • “sign up to our regular newsletter”

Be careful with your formatting and punctuation

Using exclamation marks!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! in the message body or the subject line can cause your message to be marked as spam!!!!!!!!!!!!!!!!!!!!!! (or at least deleted without being read). Along WITH TYPING EVERYTHING IN CAPITALS, overuse of exclamation marks is SHOUTING in typographical form. Nobody wants to open an email to be shouted at.

Using red or green fonts can also be picked up as potentially spammy (So be careful with your Christmas email messages), as can using white font. White font on a white background can be used (by the unscrupulous) to add keywords to a page to improve search ratings.

Particular words and phrases can be used to identify a message as spam. Look through this list of spam trigger words and see how many of the phrases you’ve used in emails in the last few months.

Spam filters will also look at the html code of your message, mismatched or uneven coding (for example, copy mailing content from a variety of places) can be taken as an indication of a spammy message. If it’s your job to regularly send bulk messages for your organization it may be worthwhile to learn about html. Free online courses that can be taken anytime can be found at Codecademy or the w3 schools site.

Always take the time to check your message for spelling before pressing send. Spelling mistakes can also flag your message as spam.

Mailing content and Attachments

Avoid embedding videos or forms in your message. The extra coding needed to get those to work can be used by senders to infect your computer with a malicious file.

If you need to share documents with your contacts, upload the document to your website and then include a hyperlink to it in the mailing. Attachments are used by the unscrupulous to infect other people’s computers, so adding attachments to mailings looks bad from a spam filter point of view.

Spam filters also look at the ratio of text to images in a mailing. If the mailing content consists of one large image (or contains a lot of images and not much text), it can be marked as spam. Additionally images sent without alternative text added, can also be an indication of spamminess.

What you can include

There are somethings you can include that can actually help convince the automated filters that you aren’t sending spam:

Personalise your mailing with tokens

With Civimail’s tokens feature you can personalize messages with the recipients name. Including extra data beyond a simple email address will show the filter that you hold further details about the recipient and are not sending an unsolicited mail to a new contact.

Give people a way to get off your mailing list

Making sure the Opt-out and Unsubscribe links in your mailings are working allows your contacts to manage the messages they recieve from you and is an indication of a well managed mailing list.

Adding a link to let people view your mailing as a webpage also helps improve your spam rating. (Opt out links, unsubscribe options and view as webpage tokens are all configurable in CiviCRM).

Managing your mailing list

Getting a lot of bounces from out of date or unmonitored email addresses can be a sign that you are using mailing lists provided by other people. Only use your own mailing lists, not those provided by a third party. If people sign up to a mailing list and there is a delay before they receive a message they may forget they’ve signed up and mark your mail as junk.

Making sure your mailing list is up to date and well-maintained will help improve your spam ratings.

Allow a double opt-in process for people signing up to your mailing list. After they’ve completed the form they should be sent a follow up message asking them to confirm they are the person that signed up, and that they are happy to receive information from you. People who sign up via this process are less likely to mark future mailings as junk or spam. This process can be handled automatically by CiviCRM.

Consider sending an automated message to new mailing list contacts, telling them how frequently you send messages and the type of content included. You can use this message to ask contacts to add your mailing list to their address book. Email filters can also check that a message comes from an existing contact.

Knowing how frequently to expect messages from you will make you a more trusted sender and less likely to end up as junk, however you need to be careful you stay true to your intentions. Someone who signs up to receive funding information fortnightly, but ends up receiving weekly mailings about training course; may end up marking your messages as spam.

Anyone recieving an unexpected message can report you to the Information Commissioners Office, and leave you open to a fine. So it's worth reviewing their definition of what is an unsolicited email.

Tools to help you gives your mailing a rating from 1-10 (10 being perfect) and gives feedback on what you can do to improve your rating. use this to look up your domain name and see if you are featured on any blacklists

Other resources