Global Distributed Mail Delivery Network


Twenty percent of legitimate email never reaches the inbox. Blame the ISPs‟ ongoing fight against spam—and then, look in the mirror. Today, your sending practices play the major role in determining whether or not your email makes it to the inbox.

The crude, content-based tools that ISPs used to counter the “spam crisis” are no longer the main factor in determining whose mail gets through. ISP relationships aren‟t that important any more, either. It‟s your sending reputation that drives deliverability, and your reputation is all about your numbers.

  • The Data That Drives Deliverability

    A study found that 77% of delivery problems were based on sender reputation. That reputation is based on five very concrete data points that each ISP looks at when assessing the email sent into their system:

    Spam trap hits: Spam traps are old inboxes that ISPs reactivate specifically to trap spammers. Since these addresses have never been registered to receive email, any mail that lands in the trap inbox is spam. The major cause for inclusion of spam trap addresses on a mailing list is poor list hygiene. Spam trap addresses may also come from a purchased list if questionable practices were used to assemble that list.

    Complaint rates: How often do people hit the “report spam” button when they receive your messages? Small variations up or down can have a dramatic effect on your inbox performance.

    Authentication: Authentication lets an ISP know that the sender is who they say they are. Spammers spoof email addresses; when email is authenticated, the ISP knows that the return address is the actual sender. Authentication is an easy first step to improving your reputation, and it can make a significant difference. But, authentication alone isn‟t enough. Many spammers authenticate their IPs so you have to be doing all of the above in addition to authenticating your mail. There are three major approaches to authentication: SPF (AOL), Sender ID (Microsoft) and DomainKeys Identified Mail, aka DKIM (Yahoo!). You‟ll need your IT department to help you get this right.

    How important is content? It depends on the ISP. We have found that some ISPs now appear to give little or no weight to content (these include AOL, Roadrunner, Bell South, Gmail, ATT, NetZero). Others give content some weight, but only a few give it a weight of 25% or higher (including Adelphia, Cox, Hotmail, MSN).

  • Protect Your Reputation: Monitor!

    When content was deliverability king, everyone learned to monitor their email for content filter triggers before hitting “send.” Today its more important to monitor deliverability from the viewpoint of sender reputation.

    Monitoring is the only way to know whether your mail is reaching the inbox. If you‟re only looking at open rates, you‟ve only got a piece of the story. If a message wasn‟t opened, maybe it never reached the addressee. It might be ending up in bulk folders or just lost in the ether. Monitoring tells you what the situation truly is.

    The only effective way to get a full picture of what‟s happening is to use seed email accounts—accounts created by a monitoring service with each of the ISPs. These accounts have good addresses, so if you send mail to them and it doesn‟t get through, look to your sending reputation with the relevant ISP.

  • Repair Your Reputation: Fix the Problems

    When monitoring reveals a reputation problem, take immediate action. Start by preventing or eliminating “unknown user” addresses on your lists:

    On the registration form for your permission-based email, require recipients to enter their addresses twice, to ensure accuracy.

    Send a welcome message to everyone who registers. Pull any bounced addresses off your lists immediately.

    Implement and maintain list hygiene processes.

    All of these not only lower your hard bounce rate, they also reduce the chance that your email will get caught in a spam trap.

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