1. Flight School Friday: Developing for Deliverability



    Last Friday, we talked about how marketers can use a reconfirmation email to clean their lists and improve deliverability. But don’t think you’re off the hook, developers. Deliverability is not just a term for marketers. There are a number of API “hacks” that can be done to boost your deliverability rate.

    But first, what exactly is deliverability? It’s the number of emails that are successfully delivered into the inbox. The higher your rate, the more customers you are reaching. There are many factors that play into the success of an email landing in the inbox - ISPs, throttling, bounces and being marked as spam. A high deliverability rate requires being on top of latest email trends as well as regular maintenance. But more importantly, it takes a lot of teamwork and communication between your deliverability, marketing and IT teams.

    Here are some API use cases that your team can set in place to help automate the deliverability process:

    Remove bounced addresses

    Use Mailjet’s Event API to track and remove bounced addresses from your contact list:

    1) Create a webhook. This tracks all of the important email KPIs (clicks, opens, bounces) and does a post request each time a customer interacts with your email.

    2) Then, do a call to our API to remove bounced email addresses from your master list.

    A high bounce rate can damage your sender reputation with ISPs, because it typically indicates that you might be practicing spammer behavior. There are a variety of reasons why an email might bounce; a more legitimate reason being that a customer mistyped their email address, but other times you’ve emailed a spam trap. A spam trap is when ISPs recycle an old, inactive email address that is no longer in use to catch spammers that buy or rent old email lists. Even if you are following best practices, when a customer opts-in to your mailing list and stops using their email address or switches over to a new address, you can potentially fall into this trap. Regularly cleaning your lists will help sweep for these inactive email addresses.

    Create Rules & Segment

    Even better, combine the Event API and Send API to segment inactive customers and re-engage them with a triggered email. Using the Event API, you can create rules to automatically filter out inactive customers (typically customers who have not opened or clicked an email in the past 3 - 6 months) and then connect this to the Send API to send a “We’ve Missed You!” email.

    Re-engaging customers will not only lower spam complaint rates, but also helps you leverage untapped revenue. The average unsubscribe rate is 20% - of this percentage, there are customers that might simply just be overwhelmed with a full inbox or have forgotten the value of subscribing to your emails.


    Using the Send API, you can create rules to personalize emails with customer data. Code emails to address a customer by name in the subject line, or refer to their last purchase/action on your site.

    To personalize, be sure that you are already tracking this customer data somewhere in the sign-up funnel and that your email lists are well organized before you upload them onto your account.

    Personalizing emails with customer-specific content will drive higher opens and clicks, resulting in a higher sender reputation with ISPs.

    Let us know what other API “hacks” you’ve used for deliverability in the comments below!

  2. Flight School Friday: Reconfirming for higher deliverability


    By Udeme Ukutt

    In the world of email deliverability, you’ll hear a lot about list management (cleaning email lists, list quality, list sources, subscriber consent, etc). One way to clean your list is by sending a reconfirmation email - which is what we’ll discuss in this blog post.

    Generally speaking, every three to six months you will find inactive users who have not clicked or opened emails within that timeframe. The goal is to reconfirm with these users whether they would like to continue receiving communication from you. The benefit is two-fold: even if you potentially lose some users, your list quality will improve because those that reconfirm are more engaged and it improves your reputation since spam complaints are lower with these engaged customers.


    Include a clear and simple call-to-action

    We like this email from Free People because they keep the “ask” simple and their confirm/unsubscribe buttons really pop.



    Remind customers why they should keep listening

    This Crocs email does a great job of explaining how their customers have benefitted from receiving their emails in the past. Beyond just incentivizing customers to confirm their subscription, Crocs also offers a 20% off discount to drive sales.


    Once the campaign is complete, remember to remove all email addresses who unsubscribed! Here’s how to do this in your Mailjet account:

    First, go to your campaign page and select the re-confirmation email you’ve recently sent out. Then, scroll down to the “Emails list” and click the drop down on the right hand side to select “Status”.

    Screen Shot 2014-09-05 at 12.15.11 PM.png

    Next, at the bottom of the page, you’ll find buttons to export your list. Click “Export to a list” to choose the master contact list you would like to update and select “Select New Contacts, Ignore Unsubscribed Contacts”. Click the green “export” button and you’ll have yourself a clean, updated contact list! As always, be sure to follow deliverability best practices and be sure that your list does not include any email addresses bought from third-party lists.

    Screen Shot 2014-09-05 at 11.36.27 AM.png

    Remember that this is a continuous process, so you will want to check back on the progress of your resubscriptions every few days or so. But it does get easier as you go, because once you have a template set up you can easily schedule this email as a triggered campaign to inactive customers every three to six months.

    We’d love to hear about some cool reconfirmation emails you’ve built! What did you found worked and what didn’t work as well?

  3. “noreply” emails: They Don’t Make Any Sense!


    Out of the dozens of emails you receive daily, you’ve likely received an email from a no reply sender before. It looks something like this; “noreply@dns.com”. The purpose of the no reply is to prevent recipients from being able to reply to the message, often relieving some of the burden from the Marketing team. But in reality, the no reply does more harm than good for companies that still use them.

    Why does it exist?

    Most advocates of the “noreply” argue that keeping the senders email address disconnected from an inbox helps to limit irrelevant replies (especially automated replies, such as subscribers’ out-of-office messages). When you send thousands of emails daily, it can become time consuming to sort through these automated messages.

    Another reason companies favor this approach is that they feel the “noreply” gives off the impression that they are a large corporation with efficient processes; separately defined channels for outbound and inbound communication.

    Other times, “noreply” addresses have been set up by tech teams on the back end, without any strategic marketing input. In other words: technical teams create those addresses for some reasons; marketing teams do not notice.

    These more or less valid arguments do not justify the fact that a one-way conversation has been imposed on the recipient. Email is historically a two-way conversation, and that is still the favored way of communication for many people. Denying your users this opportunity for a personal interaction disables one of your best lead conversions.

    Email = exchange

    By making the exchange with your company difficult, the client’s engagement with your brand is diminishing quickly. The user will be conditioned to disregard“noreply” messages, since you are implying that his or her feedback is trivial. There is a risk that users will mark your message as spam.

    As a brand, it is in your best interest to take user feedback into consideration. Your users engage with your product often, maybe on a daily basis, and can suggest areas of improvement or affirmation on features that are especially helpful to have. By establishing dialogue, addressing issues in a constructive way and answering both positive and negative comments, you build a trustworthy public image. These feedback is invaluable; you will have a better understanding of your users’ needs and be able to adapt your strategy accordingly.

    Communicate to improve your deliverability

    By communicating on a regular basis with your customers, you build a trust relationship. You are not an anonymous brand with blurred lines, but a person who answers, guides, suggests… If the relationship is strong enough, you can even ask them to add your sender email address to their contact list.

    Your campaign will look like a classic dialogue between two individuals. It is essential to understand that ISPs analyze email engagement activity to determine sender reputation. If communication is unilateral, the sender is identified as an email marketing sender. However, if there is a deeper two-way interaction between the sender and the recipient, your reputation will rank higher. As your reputation grows in the ISP, so does your deliverability*!

    The automated answer problem

    To back up a bit and address the automated out-of-office issue, simple technical solutions exist. You forward all incoming emails to an web solution that sorts out most of the automated answers. You can also set up a filter to neatly categorize incoming messages (automated answers, legitimate messages, notifications…).

    With these points in mind, you know that you have no reason to send those bothering and inefficient “noreply” emails. Exchange with your clients and convert your leads. After all, this is what email is all about.

    *Deliverability: The amount of legitimate emails you deploy that make it to the inbox (other email factors such as bounce rate, spam come into play). Deliverability is relative to the sender’s reputation: the better the reputation, the better the deliverability.

  4. Meet Mailjet’s Deliverability Pilot


    Do you ever wonder who stands behind Mailjet? Mailjet serves over 16,000 global clients and all the work isn’t done by our robust cloud platform alone. We have a dedicated team of experts that maintain continuous compliance and improvement of Mailjet’s services, aligned with industry best practices. Every now and then, we take a moment to take a closer look at the folks who constantly strive to improve your email delivery. Today’s turn is in fact having his 1 year anniversary at Mailjet as we ushered in 2014, and we are happy to have him on board!

    Udeme Ukutt, Deliverability Director

    Udeme steers Mailjet’s Deliverability & Abuse Team operations with a special quest: ensure consistent aligned with day-by-day global deliverability best common practices. His team continuously handles multiple responsibilities around the clock, like:
    • 24 x 7 abuse desk ops across multiple continents to combat anomalous (spam & phish) activities & stop the bad guys

    • continuously analyze how legitimate, solicited good email get delivered to those who want it - successfully into their inbox folders.

    Since deliverability is a core, complex and important topic, Udeme has one of the busiest jobs at Mailjet. Nevertheless, he is given a few moments to give some extra insights:

    Maggie: You ADORE deliverability and love everything that comes with it. How did you find out this was your thing?

    Udeme: Someone asked me one day, ‘do you love math? Love computers?’ I said, ‘Yes!’… and here I am, breathing deliverability compliance day in and day out. Over the years I’ve learnt & experienced delivery ops on both the sender and receiver sides of the ladder. Nevertheless, I strive to contribute positively even more!

    The average Deliverability ‘peep’ analyzes A LOT of data 24/7, which made this career path a perfect match for me. Funny enough - I always loved math & statistics since I was a little kid.

    Maggie: What is your typical day at Mailjet like?

    Udeme: Every day has something exciting, something that calls for an extra cup of coffee. In fact, each day is unique like the other because we’re constantly progressing with industry trends. We’ve to do that because the industry and the average ISP/receiver consistently maintain their anti-spam filter algorithms, and in parallel we’ve to continually adapt and analyze.

    Like many have said, deliverability is an ongoing mission that’s got no magic solution, no silver bullet! It’s an ever-changing task because we encounter new senders, new data, changing algorithms … daily!

    Maggie: Part of your job is reputation management. What does that mean?  

    Udeme: Reputation management’s something with major impacts on deliverability. ISPs such Yahoo! & Gmail… down to Orange, etc observe the average sender’s reputation to determine ‘trustworthiness’.

    If a spammer uses Mailjet to deliver bad email, this can harm Mailjet’s reputation - as well as the overall reputation of our senders. That’s the reason why its not only in our highest interest - but our senders as well - to establish, enforce and maintain the tightest antiabuse algorithms as possible to protect our reputation.

    Maggie: How do you detect spammers?

    Udeme: Basically we analyze all deployed emails real-time and search for unusual deliverability issues that may trigger off spam indicators. A negative indicator may be a high volume of bounced emails; or high complaints; or vice versa. Primarily, legitimate senders use stuff like properly authenticated mail, high quality solicited lists (ideally made up of confirmed opt-in contacts. Naturally, since all recipients on the list consented to receive emails from the sender, the bounce rate should be low.

    Spammers usually send their emails to what’s classified as third-party data (purchased, rented, etc). Spammer activity is reflected in their sender’s email stats … high rates associated with bounces, spam, complaints, etc. In rare cases, it may happen that a legitimate sender encounters a deliverability issues too. If that’s the case, we would support a legitimate sender with expert advice on how to improve their reputation.

    Maggie: How can senders improve their deliverability? 

    Udeme: To mention a few common ones that help receivers and ISPs to increase mail stream ‘trust’, spot-check these occasionally:

    • Ensure you (properly) implement authenticate email using SPF and DKIM. DMARC is a new technology that’s being recognized more and more, industry-wide.

    • Confirmed opt-in list acquisition practices are strongly recommended as opposed to a single opt-in mechanism.

    • Place focus on message design, content, structure - as well as frequency and relevance of your messages

    • My guess is that you wouldn’t want to fly with a jet plane that hasn’t had a security check either, would you? Or … you’d want to fill it up with proper fuel too, right?”

    Maggie: Thank you for those helpful insights and your precious time, it’s great to have you on board! … and now let’s go back to conquering inboxes. :)

  5. [STUDY] Email Personalization: How Good Is It For Your Deliverability?



    A study recently came out that went almost completely unnoticed. Nevertheless, it raises a crucial point. The practice of personalizing email with names/places may be detrimental: decreased reading rates and inbox placement and increased spam complaints. Seems rather counter-intuitive, doesn’t it? Let’s try to figure out what’s going on here.

    The terms of the study: the evolution of email marketing over 5 years

    This study was conducted by Return Path, the world leader in the field of email intelligence. It involved more than 60 brands (Disney, Expedia, Nike, etc.) and was conducted in two stages, in 2008 and then in summer 2013. The initial aim was to compare the evolution of practices in email marketing.

    The most striking change between 2008 and 2013 regards the collection of customer data: in 2008, more than half of the brands asked for very extensive information, such as a complete mailing address. In 2013, a third of brands simply request an email address with a zip code, or maybe a just name. Marketers require less information than before.

    Among those that collect additional data, only 22% take advantage of it by personalizing messages with the name and/or location. Hence the question: what are we seeing here? Negligence or a clever tactic? To answer this question, Return Path compared the performances with or without personalization.

    Personalization may be bad for your emails

    Surprise: the more an email is customized with a name or place, the more frequently it lands in spam or the recipient marks it as spam, and the less they actually read the message. Catastrophic. Besides the time spent to manipulate custom fields, the marketer would also lose out on the final results.


    (Source Return Path, The Email Subscriber Experience, 2008-2013)

    As you know, in the future, Mailjet will offer the possibility to personalize your emails with merge tags. We have no intention of overriding this feature: here’s why.

    1- A study is not an absolute truth

    This study focuses on tens of millions of emails and a lot of brands, but that does not mean it reflects an absolute truth. This kind of work helps to make decisions, but your particular situation may be different. Return Path also explains this quite well. On the other hand, you need to ask yourself the right questions: if you spend time and energy to send emails with custom name or location fields, did you make sure you’re gaining performance?

    2- There’s personalization, and then there’s personalization…

    If we attempt to explain these figures, it is quite easy to image the following psychological reaction: when a recipient sees his first or last name or residence, he might feel attacked. He forgets that he supplied this information and has a negative reaction. But we shouldn’t confuse personalization of names/places with “personalized content.”

    One thing we strongly recommend at Mailjet is always to send more and more relevant emails. Our interface and our API allow you to know exactly what links have been clicked. In consequence, our users can create segments based on their contacts’ areas of interest. From there, it is possible to send messages that better meet the needs of your recipients. Or even more simple: you can just personalize the subject and increase your opening rates in this way.

    Basic example: an online sporting goods shop might notice that one segment reacts to all things related to “cycling,” while another reacts to all things related to “skiing.” Very simply, it’s possible to send them the same newsletter except for the subject line, to better capture the attention of each segment: “Flash sale: discount skis” and “Flash sale: discount bikes.” The content of the email must obviously integrate both of these objects. This customization is as simple as it is powerful.


    The key to success is really just to send messages that are legitimate and desired by the recipient. Personalization of the content seems to be what matters, so run your own tests! 


    This study also dealt with other practices: double opt-in, unsubscribes, etc. We recommend you give it a read; you can download it for free here.

  6. 10 HTML tips for improving your email deliverability



    Three years ago, a Mailjet team member experienced a surprising situation with one of the clients of his former employer.

    The advertiser is a well-known player in the world of e-commerce. Every element of their email strategy is finely tuned. They have fantastic open rates (25%) in spite of an aggressive campaign (3 newsletters each week and 2-4 partner mailings each month). However, they experienced a serious deliverability problem. Yahoo! is the problem, which is surprising because Yahoo! constitutes a very female-orientated segment, which is also the target market of the e-commerce site in question.

    For four months, every possible solution is tried. With each sending, a different element is tested…to no avail. And when we try to make direct contact with Yahoo!, no response.

    The solution? To host the images of the emails…on the emails’ sender domain name! Finally, everything is back in order.

    Unbelievable, isn’t it? And yet, this kind of situation happens all the time.

    HTML: How does it influence the deliverability of your emails?

    • Observe HTML standards – Just because it is recommended to code your emails like you would have 10 years ago doesn’t mean that you shouldn’t respect the standards.

    • No javascript in your emails – First of all, because it serves no purpose, and secondly because it will incur the wrath of most anti-spam filters.

    • Properly close your HTML tags and embed them correctly – Yes, this is related to the first point, but all too often we see this type of atrocity in emails: <a href=”mysite” target=”_blank”><strong>My Link</a></strong>

    • No need to use tags predating HTML 4.01 – Actually, the use of <u> has been discouraged…since 1999!

    • Don’t use Iframes, plugins, … - Again, it doesn’t do anything, and it also gives anti-spam filters the impression that the content sent in the email was taken directly from a webpage.

    • Host images on the domain name sending the emails - This is the case described above; the more coherent your identity is, the more anti-spam filters will trust you.

    • Erase evidence of tools used to create your HTML - Especially in the case of MS Word or worse…Frontpage (not sure if anyone still uses it, but we can never be too careful).

    • Do not leave the title tag empty - The ideal is to use the email subject.

    • Use significant contrast between the text and background colors – A link in dark gray on a background of slightly less dark gray? Do you have something to hide?

    • Additional tip, check the list of tests of SpamAssassin, well-known anti-spam filter (search with the keyword HTML on the page).

    This last tip will help you better understand the “spam score” that is displayed with your campaigns on Mailjet’s interface. In fact, this score is generated using SpamAssassin tests.

  7. Deliverability Advice: How to avoid the pitfalls of inactive contacts?



    To begin, in the world of email, what exactly is an inactive contact? We can define this term as an email address that has not been reactive for a certain amount of time, whether positive or negative. The problem with inactives is that they can have a negative impact on your email sending reputation. Basically, the greater number of inactives you have on your email lists, the lower the rate of reactivity among your subscribers, which is a determining factor in your reputation.

    That being said, marketers don’t like to delete contacts from their lists! However, this potential loss can result in a significant improvement in deliverability (from the rest of you contacts) and thus, your campaigns’ results.

    After how much time should an address be considered inactive?

    This is a question that doesn’t have a definitive answer. From the perspective of ISPs, the common response is six months, but this figure can range from 3 to 9 months, according to specific business needs. In B2B markets, given the elevated value of a contact and the often more time-consuming purchase cycles, it isn’t unheard of to consider an address inactive only after one or two years from the last reaction. But, one should be aware of the potentially disastrous results from such practices.

    In order to understand why your subscribers are inactive, it is interesting to analyze those who become active again after several months of inactivity. What event sparked this reaction? If you have the necessary data, it could be very enlightening to see if an action outside the realm of email set off the reactivity, for example a telephone contact, a visit to an actual point of sale, or a campaign developed via a different channel.

    Different strategies to implement:

    • Segmentation: It is important to handle your inactive subscribers differently. This allows you to test the best reengagement tactics vis a vis your offer.

    • Unsubscribe programs: If the different reengagement strategies fail, it may be time to part with certain inactive contacts for good. But it isn’t necessary to delete them overnight! Implementing a last chance program is a good technique to tempt your subscribers with your offer one last time. In this case, use subject lines like: “We haven’t seen you in a long time! Should we say good bye?”

    • Updating your lists: This is the final, but inevitable solution: to cease communication with your inactive consumers.

    • Other strategies: These other strategies should be implemented before your recipients become inactive…and sometimes even before they subscribe. For example: improve the promise you make at the time of subscription, implement a double opt-in procedure, initialize a welcome program, analyze your recruitment channels, make the unsubscribe button more visible…

    As is often the case in emailing, commitment remains the main buzz word: the more your subscribers are passionate about your emails, the fewer your worries. The more honest you are from the beginning of your relationship, the more your subscribers will trust you.

    In conclusion: Never let your email contacts lie for several months without using them! If you do, you are risking being blocked: first, because you may not have had the chance to edit your contacts after bounces, and then, because certain subscribers may have “forgotten” that they subscribed and will flag your emails as spam.

    Photo Credit : Domaine Public - United Kingdom Government

  8. Deliverability Alert: Your Whois Should Be Made Public


    If the Whois of your domain name is set to private/anonymous, you should act as soon as possible: you need to make it public. Otherwise, your deliverability may suffer drastically, if it isn’t already the case…

    What is a private Whois?

    Certain domain registrars propose to anonymize your Whois by making it “private.” This allows you to hide information about the entity or person holding a particular domain name. 

    By default, a Whois always gives information about the owner: the name of the person or organization who holds the domain, address, etc.

    Example: with the Whois, you can know that “mailjet.com” is held by “Mailjet SAS, 30 rue Blondel, 75010 Paris, etc.”

    Deliverability issues because of private Whois

    Our deliverability team noticed that domains with private/anonymous Whois information are more susceptible to suffer blocking and/or blacklisting. European and French ISPs are particularly affected. 

    Make your Whois public as soon as possible

    If your Whois is in private/anonymous mode, we encourage you to make it public ASAP.  If you are not yet affected, you will be soon. Note that ISPs can take up to 7 days to  take changes into account. It is thus necessary to act as quickly as possible.

  9. Need To Explain Mailjet To Your Friends?


    I’ve just finished a nice presentation explaining briefly what we do and where our added-value is. Check it out! It is quite interesting :-) 

  10. Interview of Julien Tartarin, Our CTO / Founder On doeswhat.com


    How would you describe Mailjet in under 50 words?

    Mailjet is a Cloud-Based service. We send, track and deliver emails. Our service is easy to use and easy to integrate via SMTP or with our API. We focus On real time and deliverability. We’re an all in one solution: Mailjet sends all your emails: bulk and transactional.

    What made you decide to start working on Mailjet?

    Sending email has always been easy, but during these last years, delivering it to the inbox has become very complicated. I’ve realized this in my previous jobs where I needed to configure and optimize email servers. 

    According to Return Path, more than 25% of legitimate email doesn’t reach the inbox. This can be disastrous (think about apps, online retailers, etc.).

    For developers, making sure that email is getting delivered represents a huge amount of work. But they often need to focus on their product rather than on email delivery… 

    Read the whole interview on Doeswhat.