Sluit dit zoekvak.

Email Best Practices

Despite the availability of different online channels to reach out to a large audience, email is still considered the most effective channel to communicate with customers and prospects. This is mainly due to its familiarity and usage over the past three decades. Besides this it is considered more reliable over any other digital platform.

In order to use email as a successful marketing tool it is essential to know about email deliverability and the factors to increase its success rate. Email deliverability is a metric that indicates the number of emails that reach a recipient’s inbox instead of getting bounced or landing in the spam folder.

This topic is even more relevant in current times when most organisations have switched to In-Home Usage Tests (IHUTs) which requires to send more emails to their panelists instead of conducting the tests at their facilities. To ensure a higher participation rate in your sensory or consumer study it is important to know if panelists are receiving your emails in their inbox and not in their spam folder. There are a few factors that affect this email deliverability:

Special Characters

Using special characters, symbols, unnecessary punctuation (!!!) and all upper-case characters in the email subject can already trigger a spam filter. If you want to add a link in the email, then add the entire URL instead of using a URL shortener. Limit the use of big images which increases the email loading time and reduces deliverability.


Sending emails to inactive audience members is also something to take into consideration when emailing your panel. If users stop opening emails or clicking on the links that have been added in your email, ISP’s (Internet Service Provider) might consider such emails as spam. ISP’s monitors the user’s engagement and click rate and if that were to drop, it would place your emails in the spam folder in the future.

High email frequency

Sending a high volume of emails at one time can result in these emails being flagged as spam. The number of emails that is safe to send per day depends upon your email service provider (ESP) and its reputation. Instead of sending out all emails at once, consider sending them in batches.


When sending out emails, always provide an option to unsubscribe. It is important to provide this possibility to users so that they can opt out of receiving your emails if they are not interested anymore. Lack of this option will force users to mark your email as spam.

If you are sending emails via EyeQuestion then you can add the “unsubscribe” or “removeAccount” placeholder in the email footer. This can be found in the Email Settings (Administration>Settings>Properties). When panelists unsubscribe, they will not receive emails anymore but their account will remain active. When panelists click on the remove account link, their account will be immediately removed.

Similarly, EyeContact also as an option to add a default Email Footer. This setting can be accessed if you login as System Manager.

In order to add the Unsubscribe placeholder, highlight the text you want to link to the placeholder, click on the highlighted icon (as shown above) and manually add the placeholder ${unsubscribe} in the URL field.

In order to add the Remove Account placeholder, highlight the text you want to link to the placeholder, click on the highlighted icon (as shown above) and manually add the placeholder ${removeAccount} in the URL field.


Authentication is very important to ensure that emails are not marked as spam. Make sure your email server supports the SPF (Sender’s Policy Framework) protocol which determines whether the sender’s IP address is authorized to send emails from that domain.

For SAAS clients that use EyeQuestion’s SMTP configuration, please make sure to use our domain (for example: [email protected] or [email protected]) in the field email return address (as shown below). If you want to use your company’s domain then you need to add the SPF record in order to avoid the outgoing emails being marked as spam.

Hard bounce

Hard bounces occur when you send email to an email address that does not exist. A high number of hard bounces can affect the sender’s reputation and conclude them being marked as a spammer. To avoid emails being bounced, monitor your email delivery. For SaaS clients this is all done internally and we will advise you if there is any cause of concern. For clients that have their server on premises, ensure your IT department has this correctly monitored.