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What's up Wednesday: Greylisting

In our new video series “What’s up Wednesday,” we’ll give you a quick video overview of a concept that we often get questions about at Experian Data Quality.

What’s up with…greylisting?

Greylisting is a method used by Internet Service Providers (ISPs) to defend their users against spam. While the concept can be quite technical, it is important for marketers to have an understanding of how greylisting can impact their email campaigns.

Here’s how it works. When an ISP doesn’t recognize an organization that is sending email to their users, they want to make sure that you aren’t a spammer. To protect their users’ inboxes, the ISP will temporarily block your messages until they can verify you are sending legitimate emails. This is called greylisting.

If an authentic email server recognizes that it has been greylisted, it will wait a period of time and then try to send the emails again. This proves to the ISP that you are, in fact, a reputable organization and they will accept the email. Alternatively, when a spam email server sees that an email wasn’t delivered, they do not try to send the message again – they just move on to the next batch of email blasts.

If you do notice that your emails are being greylisted, it does not mean they’re being blocked entirely. The ISP is simply taking steps to confirm you are sending legitimate emails. As you build a strong reputation with the ISP, you should stop experiencing delays.

Greylisting rarely causes major challenges for email marketers, but it is important to be aware of it – especially if you are starting a new email strategy and sending time-sensitive messages to your customers.

Want to learn more about other factors that could be affecting your sender reputation and deliverability? Check out our whitepaper, 5 tips for improving email deliverability.