Understanding and Improving Email Deliverability

Updated for 2014!

Neither “snow nor rain nor heat nor gloom of night” might stay the U.S. Post Office’s couriers from delivering the mail entrusted to them, but it’s a cold fact of the digital world that email has no such steadfast guardians. Some electronic mail will simply never reach its destination—it might go to a bad address, get caught in a spam filter, or routed to a “junk” folder where it’s deleted or overlooked. This can be frustrating for nonprofits who work hard to nurture a list of email addresses. 

There are ways to increase your delivery rates when sending out mass mailings, however. You should already be using a broadcast email tool. (If you’re not, find out why you should be, and learn about your options, in our “A Few Good Broadcast Email Tools” article.) These can greatly improve your email’s chance of reaching the people on your list, but they’re not perfect.
So how can you help ensure people receive the emails you send them? To find out, we talked to a few experts with considerable experience in the area of bulk email delivery. We also created an email deliverability study. What we learned—and what we didn’t—surprised us.
Mail server administrators like to keep their systems free of unsolicited messages. One way they do this is by subscribing to blacklists (sometimes called “block lists”) run by organizations that create a database of computers and domains known to send spam. Every time a mail server sends an email, these lists catalog the domains and IP addresses—the numeric code that designates a particular computer—and recommend which should be denied. Mail servers basically check incoming emails against these databases and reject those from a “bad” source. Getting off one of these lists is relatively difficult, and can take some time.
One way to get on this list is to have lots of people flag your email as spam. Another way is guilt by association—if you’re using a broadcast email tool, you’re sharing an email server with other organizations and businesses whose bad behavior has the potential to negatively influence your email deliverability. Finally, the content and layout of your individual emails can also have an impact on deliverability.
Let’s look at those pieces one at a time.

If It Looks Like Spam…

Email can be flagged as spam either automatically, as by an automated scanner installed on the recipients’ mail servers or at one of the routing points along the messages’ journey, or manually when recipients mark it as spam using their email software. Preventing these from happening is one of the most critical ways to ensure your messages get through. Equally important is that if a lot of people flag your emails as spam, your entire email domain is tagged as a “spammer.” It can be very difficult to change that, which will affect all your email to all recipients, not just broadcast messages to the person who marked them as spam. 
How do you prevent your email from being mistaken for spam? For starters, make sure it’s not actually spam. It should go without saying, though it doesn’t, that your email should provide value to recipients. Don’t send email they haven’t signed up for. Make sure you provide a way to opt out in the form of an unsubscribe link. And don’t send too many emails, messages that are content-poor, or too few messages—wait too long between emails and you run the risk of recipients forgetting they ever signed up for your list to begin with.
Even if your content is good and your practices pure, some people are still going to tag your messages as spam. To an extent, this is inevitable, but good email practices can limit the risk before enough people flag messages that originate from your domain and get you added to the black list.
Prune your list regularly to remove known bad email addresses, or addresses that bounce. If someone unsubscribes, make sure they’re removed immediately. Asking people to add your email address to their contact lists can help their servers recognize your email as welcome, making it far more likely that it will be allowed through. This means you should consider sending your bulk email from the same address each time.

Choosing the Right Tools

Does it make a difference which broadcast email tool you choose to use? Yes—and no. A good service can definitely help, but as long as you choose one of the more reliable services, it’s difficult to say whether there’s any significant difference among the different vendors.
We tried to find out by creating a study to test five tools on a level playing field to see which were most likely to experience deliverability problems. After six weeks of continuous email blasts, we discovered there was not as much of a difference between tools as we thought there would be. Our conversations with a few industry experts revealed that our research wasn’t of a sufficient scale to learn what we’d hoped: though we sent out thousands of emails, the sheer volume of our blasts wasn’t enough to trigger many of the algorithms that modern mail servers use to block spam. (Some corporate accounts, and even larger nonprofits, may send emails to hundreds of thousands of addresses at a time, or more.)
Remember, you’re sharing an email server with other organizations and businesses, and their bad behavior has the potential to negatively influence your email deliverability. This guilt by association means that the history of the server that sends out your mail is important, and that’s not always easy for you to find out. What you can do, however, is make sure you’re dealing with a reputable mail service. Popular tools are more likely to get flagged as spam simply because of the volume of emails they send out, but they’re also more likely to remedy that situation when it happens. Smaller vendors are less likely to be flagged as spam, but when they are, it can be time-consuming for them to do anything about it.
In short, you should certainly consider deliverability when looking at broadcast email services, but as long as you’re using a generally reputable tool you can likely have much more of an effect on deliverability by ensuring you follow the best practices for bulk email described in this article

Email Content and Layout

The textual and visual content of the email itself matters, as do a number of good email practices related to the content, like the layout. A good broadcast tool lets you use predefined templates to create your mass mailings. Many let you customize your own templates—you can design them on your own, or hire a person skilled in HTML to do it for you, but a poorly coded template can trigger spam filters and result in undeliverable mail.
You can check your templates for broken links or obvious errors, but the best way to guard against this is to use a reliable broadcast service. If you’re working with a designer to create templates, make sure they’re skilled not only in HTML (the coding language of websites), but in email deliverability as well.
Keywords in the content itself can also trigger spam filters. If your email uses any words likely to be recognized by automated scanners as spam-worthy (like those commonly associated with junk mail, like “pharmaceuticals” or “Nigerian royalty”), your messages may not be making it through to their intended recipients. Some websites, like the open source Apache Spam Assassin (http://wiki.apache.org/spamassassin/StartUsing) will let you test your messages for bad keywords.
Certain email servers also simply reject HTML-formatted emails if no plain-text alternative is provided, which poses problems for organizations that prefer the visual appeal of HTML emails.

Wrapping Up

Bulk email is an integral part of communications and fundraising for many nonprofits. If yours is among them, you should assume that not all your messages will be delivered—that’s just the nature of the beast. But taking a few measures toward good email practices can minimize the dangers.
Be thoughtful when crafting emails, as well as when sending them. Use the right tools to ensure your domain isn’t at risk for blacklisting. And use common sense and courtesy to avoid irritating recipient—that’s a sure way to get your mail marked as spam.
This article was originally funded by the Annie E. Casey Foundation. We thank them for their support, but acknowledge that the findings and conclusions are Idealware’s and do not necessarily reflect the opinions of the foundation. Thanks as well as to the following nonprofit technology professionals who provided recommendations, advice and other help:
Colin Pizarek, Former Idealware Americorp VISTA
Cameron Lefevre, M+R Strategic Services
Nick Allen, DonorDigital
Bill Pease, GoodGuide



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Email deliverablity

Great article. Many of our high volume email marketing clients are challenged by deliverablity issues. But, as you point out, you just have to work the steps --methodically and carefully-- and you can start seeing great results.

A poorly coded template can

A poorly coded template can trigger spam filters and result in undeliverable mail. Regards Mr singh

Great tips ! I think i'll use

Great tips ! I think i'll use them for my newsletter. Julien, from <a href="http://www.tendances-de-mode.com/">Tendances de mode</a>.

Improving Email Deliverability Infographic

Brilliant email delivery article Collin and Chris. Thoroughly enjoyed the read : )

Your Blog Post

 This is interesting as i wrote about this subject recently and created a table of both email open rates and industry CTR http://bit.ly/Aq5VrG