Recent surveys leave little doubt: email deliverability remains the most serious challenge for marketers. According to research by MarketingSherpa, one of six email recipients will not receive a message due to it being mistakenly blocked by a spam filter. And that means lower response rates and revenues for the marketer’s business.

“The ability to deliver an email” (“deliverability”) has now become a science that requires constant study if marketers want their messages to land in Customer inboxes. And with providers constantly coming up with new spam filter algorithms to prevent abusers from invading inboxes with unsolicited emails, marketers have to adapt to the new standards and ensure compliance with the most recent trends and technology.

How GetResponse maintains your 99% deliverability rate

Deliverability is typically managed by two entities:

  • an ESP (email service provider), such as GetResponse
  • the actual sender, who can control the content, list quality, frequency, etc.

Every reputable ESP should take measures to help ensure Customer inboxes at Yahoo! Mail, Gmail, AOL, Windows Live Hotmail and other mailbox providers. These efforts can be broken down into the elements listed below.

Permission-based email marketing only!

At GetResponse, we believe in permission-based emailmarketing only. Our 12 years of experience working with users and ISPs has helped us develop a robust anti-spam policy which we observe and practice every day. The combination of automated system review and the human expertise of our Compliance Department prevent spammers (or careless marketers) from using our system before their messages are sent out. That’s the key to maintaining an impeccable reputation and the highest possible delivery rates. An ESP that allows spammers to use their system will see a downgrade in both user domain and provider reputation very quickly. Granted, there are fewer “bad apples” thanks to improved filter algorithms. However, hosting even 1% of bad apples can damage deliverability for the 99% of Customers who want to promote their business - and their brands - via legitimate email marketing.

Nurturing ISP relationships

In the email game, you need to team up with the mailbox providers and anti-spam organizations if you want to win. Every ESP should participate in major industry initiatives such as MAAWG, EEC and ESPC. This offers excellent opportunities to exchange knowledge and to cooperate with the ISPs (Internet Service Providers) in order to reduce abuse and create new legal and technical email deliverability fundamentals, which can directly benefit the ESP’s clients.

Top notch tools for top notch deliverability

The technical process of sending a mass email campaign and tracking its results is a complex one. This is why partnering with companies who provide top notch technology can help to ensure that the technical aspect of the delivery process is seamless. GetResponse, for example, cooperates with Return Path, which offers inbox placement solutions that tell us which campaigns land in target inboxes and which end up in junk folders, and help diagnose any related problems. Another partner, Port 25, provides world-class Mail Transfer Agents capable of sending out millions of emails in record time. There’s definitely more aspects of deliverability than addressed by these technologies, but the point is that an ESP that wants to maintain at least 90%+ email deliverability needs to monitor and invest in leading-edge technology.

Bounces, feedback loops, DKIM, opt-outs...

A clean list is the key to first-rate engagement and consistent inbox delivery. That's why a reputable ESP should automatically process all unsubscribe requests and bounces resulting from your sends. At GetResponse, we instantly remove all undeliverable addresses and subscribers that wish to opt-out from further mailings. It ensures CAN-SPAM compliance and reduces the risk of spam complaints affecting domain reputations.

As mentioned earlier, there's more to the technical side of deliverability that merits close attention by anyone planning to invest in an email marketing service. GetResponse also authenticates messages using SPF (Sender Policy Framework) and DKIM (Domain Name System validation format), which are required by ISPs but, more importantly, reduce the risk of forgery and of client emails landing in junk folders or being blocked.

Last, but not least, ESP participation in ISP feedback loop programs (FBLs) is a definite must. GetResponse establishes feedback loops for every client whereby ISPs notify us whenever someone marks an email as spam, so we can instantly remove that subscriber from your list.

10 steps you should implement to improve email deliverability

Since you already know what your email service provider can do for you in terms of deliverability, it's time to ask yourself a question: How can I help ensure that my email campaigns are not blocked or routed to junk folders?

It may come as a surprise to some of you, but in today's email world, it's the sender that has the biggest influence on deliverability, not the software. In other words, you might be using a premier ESP, with amazing features and an impeccable reputation, but if your mailing list is of poor quality, or your emails are tainted with content issues, you may never experience seamless inbox delivery. No software can solve the sender's content or list problems, period.

Therefore it's up to marketers to evaluate their mailing practices and review the current state of their email programs on a regular basis. Below we have listed 10 tips that should become your checklist for maintaining the health of your email program and avoiding deliverability issues.

Sending IP address and domain reputation

Mailbox providers rate senders based on two key factors: the reputation of an IP address and the domain from which the emails originate. Inbox providers such as Gmail or AOL keep a record of what kind of emails are being sent from a particular IP address. Their scoring system is similar to the one used by banks in credit score rating. If you build a strong and positive history of your IP and domain by sending solicited, relevant emails, you are most likely to enjoy relatively undisturbed inbox delivery. However, when your mailings are too frequent, your list hygiene practices inadequate, and no one opens your messages, there's a high probability your sending IP address score will fall through the floor and no ISP will allow you to enter the inbox area.

This situation does not concern those who use a professionally monitored, shared IP space, such as clients. However, if you are on a dedicated platform, you should definitely monitor the reputation of the IPs and domains from which your email campaigns originate to ensure the good standing of your sender reputation.

Hint: For more information on this important step, you might find the resources below useful:

  • Return Path's Sender Score (
  • Cisco's SenderBase (
  • McAffee's Trusted Source (
  • (

List Quality

Many companies are keen on purchasing lists of “fresh” email addresses to expand their field of prospects. It appears to be so much faster and easier than building up an organic list from their own trusted sources. They're simply not aware of the problems purchased lists can cause - until it's too late.

People only respond well to emails they've requested - or what we call "permission based emails". No one likes to receive unsolicited emails from vendors, known or unknown. It's an invasion of inbox privacy that could lead to more serious offenses, like unwittingly giving someone permission to sell and resell one’s personal data to strangers for a couple of dollars.

Sending campaigns to purchased lists riddled with dead and inactive email addresses could damage your reputation beyond repair, and eventually lead to losing inbox access - and even domain blocking in the long run. Purchased lists are also full of spam traps - addresses created not for communication, but solely to "lure" spam.

So, again, the key word here is permission. Growing your list organically via web sign up forms will guarantee that your leads are fresh and responsive. After all, they are consciously opting-in to receive information from you so you know they are interested and pre-qualified to receive offers.

Hint: We encourage you to read up on best practices that support organic list growth and to download our list building white paper "How to Grow Your Email Marketing List".

We think you’ll agree that organic growth is the safest and most effective way to build a successful mailing list.

Content Issues

Sometimes the issue with deliverability may not be due to mailing list quality or IP reputation, but with the message content itself. Now “content” covers a lot of areas and functions of a message. That’s why, when you deploy your email marketing campaign, the receiving servers put it through a wide range of spam filters that analyze:

  • the frequency of potential spam words
  • reputation of links in your email
  • image-to-text proportion
  • size of your email
  • reputation of image hosting services that you use
  • with more being added all the time.

What can you do to help eliminate these problems before you hit the send button? Try the following methods:

Hint: make sure that the content that you create is engaging and relevant, from the subject line through the last sentence. Senders that get high response rates are more likely to have their broadcasts delivered to inboxes by service providers. Conversely, if senders persist in targeting non-response inboxes, their messages could be blocked

  • use the GetResponse SpamScore Check system. It will assign a score to your message copy assessing the likelihood of it ending up in junk folders due to content issues.
  • use services such as ( to check the reputation of the links in your email. If any of them are found on prominent blacklists like URIBL, SURBL or Spamhaus, you can be sure that your message will struggle with inbox delivery.
  • host your images and documents on GetResponse Multimedia Studio. It’s an abuse-free hosting service that will not affect email delivery in any negative way.
  • make sure that you include at least one short paragraph of text in the message copy section of every large email. Sending an image-only newsletter is a common tactic used by spammers to get past content filters, but most email services and ISPs have developed filters for this gimmick.

FROM field address reputation

This is a hot topic these days! The GetResponse Email Solutions Team has examined and discovered that your FROM field address might influence whether your email lands in an inbox or the junk folder. This is especially characteristic of Yahoo! Mail and, during our tests, we even noticed different results for the same email sent with the address and addresses.

The main takeaway for senders is that they should stick to one, easily recognizable FROM field name and address. It has to have a decent reputation built by sending solicited and engaging emails over time.

Hint: If your campaigns are struggling to reach inboxes at certain ISPs, you can try tweaking the FROM field address and testing it with the same creative. This will tell you whether a tainted FROM field might be the root of the problem.

Ask recipients to whitelist you

Did you know that when a recipient adds your FROM field email to their address book, all your messages will land directly in their inbox? While that may seem obvious, many marketers still waste this great opportunity to increase delivery rates! And it’s so easy.

Simply remind your subscribers in the email preheader section that they can “whitelist” you by adding the address to their address books. It’s also a good idea to provide brief instructions on how to add an email to the address book. By getting on the “allowed senders” list, you will be released from the constraints of spam filters, so it’s worth the minute or less it takes either party.

Hint: The first email you send out right after a subscriber opts-in to your list (the welcome email) is the perfect time to ask for whitelisting. Get in the habit!

Avoid gimmicks!

It’s that simple. Permission based email marketing means no gimmicks. And trust me, ISPs these days really know how to tell which sender is using tricks to get their email delivered. In fact, it’s quite common for those caught in the act to suffer the worst possible punishment: an IP / domain block preventing any further emails from being delivered.

Among the gimmicks that should be never be part of any legit email program are:

  • hashbusting (randomly adding certain characters within the mail subject line / content to fool the spam filters, e.g. “F.ree. p.r!z.e”)
  • deceptive/ trick subject lines, e.g. starting the email message with “Re:” or “Fwd:” in order to create the illusion of previous communication initiated by the sender.
  • dishonest/ misleading claims, e.g. subject line states the recipient won the prize while the copy says that there are conditions to be fulfilled in order to claim it.
  • including the text message within one large image to fool the spam filters.

Reduce risky words to nil

You’ve probably heard this one before. Over-using words such as “free”, “prize”, “bonus” in your newsletters can hinder it from reaching Customer inboxes. Although ISPs today are smarter than ever and analyze more factors than just message copy, you still need to keep an eye on those pesky spam words. The GetResponse built-in SpamScore Check will ensure that your email copy is not tainted by the over-use or placement of these words. To get a complete list of “forbidden” spam words, visit our blog.

Hint: avoid cluttering your emails with too many all-caps words and exclamation marks. This pertains especially to the subject line, so ensure that you maintain a healthy balance here (two exclamation marks is enough, one per sentence).

Rely on SpamScore Check

We’ve mentioned this a couple of times, but it deserves repeating: Spam Assassin’s SpamScore Check engine is the email marketer’s best friend!

Incorporating a whole lot of rules that it updates on a regular basis, SpamScore Check will verify the content of your emails for:

  • risky keywords
  • blacklisted URLs in the content
  • text-to-image ratio
  • and many more.

If you would like to learn more and obtain the entire set of codes used by SpamScore Check, please visit this page.

Hint: Any score above 5.0 points should set off alarms. Please always analyze the issues pointed out by SpamScore Check and optimize your newsletters. Otherwise, there is a very high probability that your emails will continue to miss subscriber inboxes and damage your sender reputation.

Monitor your deliverability

Even though GetResponse has a specialized team of Deliverability Experts working around the clock to keep your deliverability rates high, there’s no harm in monitoring it yourself. The more informed you are, the better you’ll be at optimizing your emails.

As an ESP, we leverage industry-leading tools from Return Path, which tell us how many emails land in junk folders, which ISPs have connectivity issues at a given time, etc.
As a sender, you can employ a method that is way easier and will cost you nothing.

Simply create a list of seed addresses, which are nothing more than the mailboxes and ISPs your Customers use most often. Set up approximately 5 mailboxes at every provider and attach the list of these seed emails to your regular mailing list.

After each newsletter is deployed, you will be able to log in to each seed account and verify if the email was delivered successfully by that provider. Very useful!

Keep in touch!

Last, but not least, don’t forget about maintaining a regular mailing pattern. You may be surprised at what’s considered “regular” these days. For example, did you know that sending emails once every 2-3 months can be more detrimental than sending 2-3 emails per day. Why?

  • your Customers begin to forget your FROM field name and address, deleting messages and decreasing open ratios.
  • subscribers may think that they never signed up to your emails, so they mark them as spam, and you get negative feedback.

For these reasons and more, ISPs actually prefer to see a steady flow of communication (e.g. 2-3 newsletters per week) instead of infrequent, massive “blasts” to an entire list.


We sincerely hope that this whitepaper sheds some more light on the complex and dynamic world of email deliverability. Implementing the recommendations we've provided will definitely have a positive effect on your email program and the conversions it generates. After all, even the world's most beautiful email template becomes useless if your emails get blocked or land in the junk folder!

Have a question? Talk with GetResponse experts!

GetResponse is created by email marketing experts with passion and enthusiasm to deliver a product that meets and exceeds marketers' needs. If you have any questions, you can contact our expert support by phone at 1-877-EMAIL-GR or any of the talented professionals on our team.

Maciej Ossowski - GetResponse Email Marketing
Maciej Ossowski
Director of Education