Avoid having your email invitation end up in the spam box

Our helpdesk sometimes gets questions from users afraid that their email invitation won’t reach their panel or that it will end up being marked as spam. Of course CheckMarket does all it can to make sure that your invitations and reminders reach your mail every time. But in these days of ever stricter spam filters taking precautions and testing is well advised.

These days, email providers are utilizing increasingly more advanced filtering technology all the time and what is new is how much importance is paid to the content of the mail.

The following tips can help you avoid the jaws of spam filters.

Unknown is unloved

Spam filters will always check the reputation of sending server first. CheckMarket strives to continue to maintain a clean status, which is why we have such a strict anti-spam policy. If you are conducting an internal survey or a survey aimed all at one company, you should ask to have CheckMarket ‘White listed’. Ask someone from the IT department to include ‘*.checkmarket.com’ to their white list for the duration of the survey. This way the invitations will certainly not be marked as spam. While you are at it. Make sure that the survey is available through the company firewall.

It’s the little things

Spammers have been getting smarter too. Now they use viruses to send spam from normal people’s computers. So spam filters now look at content more and more. And it is often small details in your mail that may trigger them:

    • Avoid using too many capitals, punctuation or typical spam words (free, win, euro, € $, sex,…) in the subject line of your mail.
    • Keep the length of your subject under 45 characters.
    • Avoid using excessive exclamation marks or other punctuation in general, capitals and white space in the body of your mail.
    • Don’t use too many colours or large font sizes. Make sure that your mail is not more image than text. Your mail will look better in HTML since you can format it and add logos and banners but this will also increase your spam score. We also recommend including a plain-text version when you send a mail. Normal email programs such as Outlook generate these automatically. If a mail doesn’t have it, it will look like it came from a computer instead. In our tool you can find the plain text version just under the HTML version. This version is also used by PDA and cell phones.
    • Spam filters are mostly tuned to English. So your English email invitations require special attention. Avoid writing Dear [name] in your email as this increases your spam score.
    • Use correct spelling.
    • If you are pasting your own HTML, make sure that it is well formed and that the syntax is correct.
    • Don’t place too many different URLs (links) in your mail.
    • Never, never use an IP address in your URLs (links). An IP address looks like ‘’.

    Win your respondents confidence

    Avoid having your respondents marking your invitations as spam. Try these tips:

      • When people check their mail, the first thing they look at is the ‘From’ and the ‘Subject’. Try to choose a ‘From’ name that the reader is likely to recognize. Try to make the subject of your mail perk the readers interest while avoiding the key spam words.
      • Make sure you have permission from the recipient to send them a mail. When they are not expecting a mail from you, it will end up that much faster in the spam folder. If you are working with a fixed panel, you may want to add a question asking if the respondent wishes to participate in future surveys.
      • Don’t overuse panellists. Respect the wishes of your panellists as to the frequency they wish to be approached to participate in your surveys. Someone who asks to only be invited 4 times a year does not want a mail from you each month. We offer a filter to exclude contacts who have been invited x days/weeks/months ago. The filter is available when adding contacts to your survey under ‘Advanced options’. This will help you avoid spam complaints.

      After having applied all the above tips it is time to take the ultimate test and send some trial email invitations to a test panel.

      When putting your test panel together have them represent as close as possible the target audience. Try to choose test panellists with a wide variety of email providers and email clients such as Gmail, Hotmail, Yahoo, Outlook, Lotus Notes etc…

      If these mails arrive in the test panellists inboxes, it’s a good indication that the wider panel will also receive the mails correctly.


      1. Subject
        • Max. 45 characters
        • Avoid: $, €, !,?, win, won, free
      2. Content
        • Avoid more image than text.
        • Never use IP addresses in URLs
        • Never write Dear x
        • Avoid malformed HTML
        • No scripts!
      3. Test, test, test
        • Send test mails to a test panel
        • Send test mails to different email providers
      4. Internal surveys
        • Ask that ‘checkmarket.com.’ be added to the spam and firewall white list.

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