What is greylisting (or graylisting)?

Keeping your clients and followers up to date ensures continued business and consistent revenue. You use your email list for email marketing and customer retention, so you produce quality content to benefit people, bringing value to their lives. You’re already aware of a variety of techniques put in place to prevent spam, but what is greylisting?

Greylisting (sometimes referred to as graylisting) is just one spam-prevention technique you can expect to encounter as you embark on your email marketing adventure. What is greylisting? It’s an anti-spam technique that places email addresses somewhere between a blacklist (flagged spammers) and a whitelist (trusted senders). Picture this: you send an email to a new address for the first time. Since you are new to the recipient server your email gets bounced, and you receive a message instructing you to retry later within a specified window of time. Assuming you follow the instructions and submit the new (additional) pass within the indicated interval, you get added to the whitelist.

Greylisting makes an excellent tool for warding off spam, since spammers typically only try once, or retry multiple times very quickly. Spammers value their time above all else, so they won’t pause to read the bounce email and schedule an additional pass (retry) within the given timeframe. Moreover, the specified interval varies from one mail exchange (MX) server to another - sometimes the interval is completely random.

Meanwhile, legitimate senders stay attentive to bounce emails and even look for ways to reduce the risk of future bounces in order to maintain a good sender score.

Greylisting shares similarities with SMTP tarpitting. SMTP Tarpitting is a process that slows email delivery down significantly to repel spammers. It takes bulk emails and delays delivery across the board, whereas greylisting gives more slack to trusted senders, resulting in a less intensive procedure.

Numerous tools help facilitate greylisting, from MX servers to anti-spam software. Some of the most common mail server options offering greylisting support are Courier, Exim, MailEnable, Microsoft Exchange, Sendmail, and Qmail. Anti-spam applications such as Barracuda, Postgrey, and SpamTitan are widely used.

 

What you can do about greylisting

Now that you understand what greylisting is and why mail servers use it, you can see why it’s such a popular technique for preventing spam. Greylisting issues could end up monopolize your time and focus if you don’t plan ahead, but a good email validation service can save you a headache. That’s where we come in.

Verifalia’s advanced email validation service offers customizable features so you can select a plan with additional passes. Verifalia will try validating the email address again later if its MX server employs greylisting. Additionally, our cutting-edge technology validates email addresses protected by greylisting, even if they only appear on the greylist due to temporary issues, such as a full inbox.

Choose from three different quality levels: Verifalia’s high quality profile gets you up to three additional passes in case of graylisting, while our extreme quality profile comes with nine additional passes. Or you can still take advantage of our standard profile at a low cost but without these premium features – that way you can use Verifalia even on a tight budget.

Explore the Verifalia website to learn more about how the Verifalia validation service can boost your email marketing efforts, overcoming obstacles such as greylisting. Register for your free membership or contact us to get started.



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