To talk about the evolution of email best practices is to talk about their non-evolution in many ways. Why is that? Well, they haven’t changed much over the last decade. What has changed is the importance of adhering to those best practices. Both the way that mailbox providers filter mail and the legal repercussions for not following best practices have evolved steadily. What this means is that getting by with the bare minimum is no longer enough to get you delivered to the inbox. Though the recommended practices haven’t changed much, they are now a requirement for good delivery.
Ten years ago, all you needed as an email sender to ensure good delivery at most mailbox providers were sound, basic, infrastructure, and a low complaint rate. These things are still important today, but mailbox providers recognized that they weren’t as effective as they could be at catching those that would abuse their users. Spammers would purchase huge lists of addresses (“millions CDs”) and mail to them, removing anyone who complained. This practice of “list washing” enabled spammers to game the complaint rate and get their mail delivered to the inbox.
Then, in 2009, the concept of overall IP reputation became the new way that mailbox providers looked at filtering mail. Instead of relying solely on complaints, they started to look at things like unknown users (550 5.1.1 rejects), TINS (This Is Not Spam) votes, content, and trusted user votes - like Microsoft’s SRD program and Yahoo’s trusted voters - to form a more detailed picture of a sender. This allowed them to filter mail more effectively, and made it harder for the bad guys to game the system. Spammers were no longer able to weight their lists with inactive accounts to artificially inflate the denominator and have a lower complaint rate. At this point, list quality became a more import area of focus for senders. Now, their delivery to the inbox and resulting ROI could be threatened if they send to users who complain about their mail or non-existent addresses.
Next, mailbox providers rolled out more sophisticated spam filtering based on user level engagement - Microsoft’s SmartScreen filter for example - by tracking things like click-throughs, delete without reading, enabling images, etc. This moves beyond simply tracking complaints and TINS votes, though those are still valuable metrics for user engagement. This level of filtering made mailing frequency a more important focus for senders. Simply blasting your subscribers with mail, even if they aren’t complaining, can negatively impact your delivery.
Authentication and Domain Reputation
Most recently, email filtering evolved to include authentication - like DMARC - and the concept of domain reputation. AOL began checking DKIM in November 2008. In April 2008, AOL included authentication with DKIM in their sender best practices. Yahoo used DomainKeys in their FBL in 2009. So, while the mailbox providers are still trying to implement authentication checks and learn how to best use authentication in their mail filtering, it’s been an established best practice for almost 5 years.
For senders, properly authenticating your mail protects your brand from spoofing and phishing attempts. While authentication is not a reputation parameter in itself, mailbox providers are looking for ways to use the data they get from authentication to help them determine domain reputations. Associating reputation to a domain allows mailbox providers to adjust their filtering for an entity as a whole, so segmenting high-quality and lower-quality mail on different IPs will become a less effective strategy for senders. Maintaining a good reputation across the board will be more and more important.
CAN-SPAM, the US anti-spam law which took effect in 2004, set forth regulations about the sending of commercial email. These include: a functional unsubscribe mechanism, non-obfuscated content and header information, and other good sending behaviors. While CAN-SPAM does not require opt-in, that doesn’t mean it hasn’t always been a best practice.
Now in 2014, the Canadian Anti-Spam Law (CASL) will come into force, and the legal repercussions of not following best practices - like opt-in mailing - will become more severe. CASL adds another layer of accountability for senders, not to mention hefty fines to the tune of $10 million! This will make properly obtaining and tracking permission from subscribers a requirement.
To sum it all up...Best practices are the foundation on which good delivery is based. They have always mattered, but now there is a bigger impact. For senders, how you build and maintain your list hasn’t changed, but the mailbox providers’ ability to tell whether you are doing it the right way and filtering based on that has evolved. This means that optimizing your email program is more important than ever.