Email Best Practices Matter, No Matter Who You Are

If you haven’t followed Return Path through the length of our existence you may not know that our original business was an Email Change of Address service. This is a consumer service in which we facilitated re-connection of email relationships after an individual had moved to a new email service – the email equivalent of the United States Postal Service change of address form for when you move to a new house or apartment. It’s a pretty cool idea, which is why we recently sold it to Fresh Address, who will keep it running. You should give it a try.

In the process of running the service for more than eight years we acquired over 20 million customer records. In compliance with our privacy policy as part of the sale we sent a Change of Control Notice to these customers. The notice informed our customers of the new ownership, and gave them the opportunity to opt-out of the service before the data was sent to Fresh Address.

All of the email addresses were collected using the double opt-in method, however it had been quite a while since many of these customers had been sent email from Return Path. In many cases, it had been years. Yes, not routinely mailing our customers flies in the face of good email hygiene best practices – the practices we regularly recommend to our clients. We see the irony. But the Change of Control Notice is a promise we’d made to these customers in our privacy policy, and it’s required by the law in some jurisdictions, so we had to send the email.

So now what do we do? We have a list of over 20 million email addresses that we need to mail who hadn’t been recently mailed. What we did was “eat a lot of our own dog food”: we used the Return Path tools and services as well as followed the advice and guidance of the email deliverability and privacy experts on our staff (many thanks to Tom Sather, J.D. Falk, Neil Schwartzman and Tom Bartel).

With this in mind we managed the mailing as follows:
Setup outbound mail servers. For outbound we used Postfix configured with the DKIM milter written by our friend Murray Kucherawy at Sendmail. We’ve had good experiences with using Postfix in the past, and DKIM allowed us to not only ensure the security of the messages, but also to formally, publically proclaim responsibility for each and every message we sent.

Setup inbound mail servers. For inbound we also used Postfix, and used the perl Mail::DeliveryStatus::BounceParser CPAN module to process bounces.

Configured DNS. Setup valid “Reverse-DNS” for the outbound servers, and implemented an appropriate SPF record – again to be transparent and accountable for the messages.

Setup standard “role” email accounts. We configured [email protected] and [email protected] addresses for the mailing domain and directed those accounts to be read and processed by our customer support team.

Signed up for Complaint Feedback Loops. Signing up for feedback loops gave us visibility into how email is being received by the consumer. The feedback loop sends a copy of complaints a consumer makes about your messages to an email address you specify. We signed up for feedback loops from AOL, Microsoft, Comcast, Cox, Mailtrust,, United Online, Bluetie and Yahoo!, many of which are hosted by Return Path. But, we went through the exact same sign-up process as any other sender.

Verified deliverability with Return Path tools. We used the Return Path Mailbox Monitor tool to verify and monitor the deliverability of our mailing. We also used the campaign diagnostic feature within the Mailbox Monitor tool to verify that our infrastructure was correctly setup (DKIM, Reverse DNS, HELO, SPF ). I realize I’m rooting for the home team in saying this, but using the Return Path deliverability tools saved us time and helped us make sure that nothing was overlooked.

Verified the content with Return Path Campaign Preview. We used the Return Path Campaign Preview tool to check to see whether our content appeared suspicious to any of the top spam filters. We also verified that the HTML of the email rendered correctly in the most popular email clients ( desktop, webmail and even mobile ). Using Campaign Preview saved us a tremendous amount of time by allowing us to verify spam filtering and rendering all in one place.

Signed up for Sender Score Certified and SafeList. After we had verified that the sending IP addresses of the mailing met the requirements of the Sender Score Certified and SafeList programs we signed up and were accepted to the programs. Here again, we were held to the exact same standards as any other sender applying for the program.

Ready? Go! The mailing went out between February 2nd and February 16, 2009.

What did we learn?

It’s not hard to be a good mailer. It really isn’t. I don’t want to trivialize the work that is needed to setup a proper mail infrastructure, but it’s easier now than it ever has been in the past. It’s pretty straight forward to setup a few mail servers with open source tools to properly send out email and process bounces.

Making sure content looks right is hard. It’s actually harder than you might think to make sure that HTML renders properly across all the different email clients. Our “creative” ( the body, or content of the message ) was put together by a very talented HTML designer and it looked great…..except when we ran it through Campaign Preview. It was fine in all of the email clients except at Hotmail where image spacing was all wrong. That was a big problem since a large percentage of the list is Hotmail. It turns out the culprit in our particular mailing was a paragraph tag that Hotmail treated slightly differently than other email clients. After changing the paragraph tag to a div tag the email looked great in all of the tested email clients. Needless to say it would have been quite sad if our creative had looked bad to so many of our recipients.

Double opt-in works. One thing that the Sender Score Certified compliance team pointed out was that despite sending to more than 20 million old email addresses we only hit two spam traps. That speaks to power of double opt-in as being the best way to avoid getting spam traps on your list.

Following mailing best practices matters. The mailing averaged a bounce rate of roughly 30%. That isn’t terribly unexpected due to the age of the list – many of the recipients’ addresses were no longer used, and had been closed or expired. However, the interesting part is that the addresses that hadn’t been mailed in over a year had over twice the bounce rate of the more recently mailed addresses. This just emphasizes the importance of mailing your list frequently and removing invalid recipients from the list.

Sender Score Certified works. I mentioned that when the mailing started the IPs we used for the mailing qualified for the Sender Score Certified program. Due to unfavorable Windows Live Sender Reputation Data rates and unknown (bouncing) user rates for the older data on the list the IPs eventually got suspended from Sender Score Certified because they no longer qualified. We saw higher delivery rates to Hotmail, Yahoo!, and other major IPSs when on Sender Score Certified.

It’s clear that the ISPs are making objective decisions; they didn’t let the mail through just because they know us, and we didn’t ask them to make any exceptions. We were sending to a relatively dirty, uncertain list, so it’s no surprise that we ran into some difficulty. From now on, we’ll make sure that every mail stream at Return Path always follows every best practice we recommend to our clients – and as our recommendations evolve over time, so will our own internal practices. Fortunately, as Matt mentioned in his post on this subject, we no longer send bulk consumer email. The remaining mailstreams are smaller and, we hope, will be easier to manage.

When all was said and done I feel we successfully fulfilled our obligation to the end-users of the ECOA service. I also have a higher appreciation for the struggles that good mailers go through every day sending email.

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