Start An Online Business - Email Marketing

 Greylisting - Yet Another Reason Why Emails To Your Customers Are Not Getting Through

If you're sending any mass emails to your customers/leads, then you should know about Greylisting.

Greylisting (sometimes spelled graylisting) is a relatively new yet widely used anti-spam method, implemented by your customers, that automatically "drops" all incoming messages coming from your email-address.

It’s based on the principle that mass email engines don't behave like a normal mail server. Normal mail servers will, if a temporary error occurs at the receiving end, buffer the email and try again later.

Mass email engines, such as the ones powering common affiliate-systems (sending a newsletter from CommissionJunction, ShareASale etc.) or help-desk systems, normally don't have this functionality built in.

Greylisting generates a temporary error on purpose and waits for the sending server to come back later and try to deliver the mail again. A normal server, waits a while, tries again and then succeeds in delivering the mail. A mass email engine tries one time and then the email is lost forever.

The greylisting mechanism keeps a database of approved senders, each consisting of sender address, recipient address and the IP-adress of the sending email server. When a new combination is found for the first time, a message looking something like this is sent back to the sending email server:

451 4.7.1 Greylisting in action, please come back in 00:30:00

Here we can see the appropriate SMTP codes for a temporary error and a descriptive text of what has happened. If the sending email server tries again before the 30 minutes has passed, it will receive a temporary error again:

451 4.7.1 Greylisting in action, please come back in 00:15:00

After the 30 minutes has passed and the sending server tries again, the email will pass and the sender triplet will be registered as “whitelisted” for a configurable duration (30 days or something like start a web business That means that subsequent emails from the same sender to the same recipient will be delivered without delay.

Greylisting is mostly transparent to your customers, besides for a small delay the first time.

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Greylisting is very effective because many mass e-mail tools will not bother to retry a failed delivery, so the email message is never delivered.

If you're using any third party tools to deliver messages to your customers/leads, make sure these tools are greylisting compatible. Our experience working with clients revealed greylisting as the #1 reason for low open rates.