Most e-mail marketers measure open and click-through rates to gauge the effectiveness of their e-mail marketing campaigns. But too often they overlook factors that reduce the percentage of e-mails that make it into a recipient’s inbox.

Major providers of e-mail addresses to consumers are increasingly focused on rewarding good e-mails by ensuring they land in consumers’ inboxes rather than just blocking bad e-mail. (Those e-mail providers, such as Yahoo, Microsoft and Google are typically called Internet service providers, or ISPs by e-mail marketing experts.)

In the past, for example, ISPs were more likely to block a high percentage of a sender’s e-mail if some of its recipients clicked their spam button. But now, if that same sender also takes proactive steps to show its e-mail is legitimate and engages the recipients, ISPs are more likely to deliver a higher percentage of e-mail to the inbox even if some recipients are hitting the spam button.

But you still need to ensure you’re taking the right steps that result in better treatment from ISPs.

Sender reputation remains the cornerstone of deliverability.

Here’s what we’ve learnt about getting e-mails delivered. I’ve laid it out, in what I believe is the order of importance, the following factors ISPs consider in scoring a sender’s reputation.

● Invalid addresses – E-mails that bounce because they were sent to invalid and inactive e-mail accounts.

● User complaints – Recipients click the Report Spam button because they don’t recognize the sender, they don’t remember opting-in to a marketer’s list, the content of the message is no longer relevant to their needs, they don’t like the sender’s e-mail frequency, or they want to unsubscribe from the sender’s list.

● Domain – Most ISPs augment their IP-based reputation systems with domain-based reputation services that rely on DK/DKIM, or DomainKeys/DomainKeys Identified Mail, which is used to validate the domain name associated with an e-mail message. Under the DK/DKIM system, ISPs can check the coding a sender places in the e-mail header with information the sender has registered with the Domain Name System, to ensure that the e-mail is being sent from the sender’s web address. This is used to guard against e-mails that, for example, may be sent by criminals who attempt to use variations of legitimate domain names in phishing attacks that lure consumers into revealing confidential information like credit card details or account passwords.

● Frequency – ISPs favour senders whose frequency follows regular patterns. Sending too frequently or infrequently will damage a marketer’s reputation.

● Volume – Sudden bursts of high volume can lead to penalties. You should segment your e-mail list into small groups and stagger delivery patterns so that all e-mail marketing messages don’t hit ISPs at the same time.

● Size – E-mail messages should be 10 to 60 kilobytes and never include attachments (plain text consistently gets the best results for us).

● Content – Even though ISPs’ text filters are not as strong as they once were, words such as “free” can prevent an e-mail message from getting delivered, especially if the other tips on this list are not followed.

● Third-party reputation services – ISPs rely on certification and accreditation services to vouch that a sender is legitimate.

● Engagement – ISPs monitor the number of recipients who open and click on a sender’s e-mail messages, along with the number who ignore or delete the sender’s messages. Thus, sending messages to inactive subscribers can hurt a marketer’s reputation and deliverability rates. Message – PURGE your list. The days of list size being equated to dick size are long gone.

● Spam trap hits – So-called spam traps are old e-mail addresses that their users have abandoned. ISPs monitor these e-mail addresses even though no one uses them, and sending to these addresses results in a lower effective delivery rate for the marketer.

● Sending infrastructure – Marketers can help to maintain good reputations with ISPs by sending e-mails compliant with RFC standards and ensuring content and links are not misleading or otherwise inappropriate. RFCs, or request for comments, is shorthand for rules for e-mail and other Internet-related operations.

As you can see there is a LOT you can do to improve your sending reputation.

100% of people reading this can go to their email client and delete all the bad e-mail addresses. Just doing that will result in a 20 – 25% bump in deliverability.

Neil