The Journey Of Your Emails This Christmas

Christmas is just around the corner – at least for the email marketer – and the time to think about your Christmas campaigns is now. Sending the perfect email to the right contacts at the right time is hard, and even harder if you don’t understand how all of your fantastic Christmas campaigns make their way into your recipients’ inboxes. So, how does the email journey work from a technical perspective? How exactly does a message get from the sender to the receiver? Well, let’s find out.


The journey to the inbox

OK, so let’s start with something obvious. Before you can send your beautiful Christmas campaigns to your subscribers, you need to create them. Groundbreaking, huh? Lucky for you, many email service providers (ESP), like Mailjet, offer editors to make designing an email easier.

So after spending some time looking up the funniest gifs and festive images, playing around with the colors and drafting the best content, your campaign is ready, its design is optimized for deliverability and it really looks beautiful. Great job! Now is the time to press the “Send” button. Scary, right? Well, wait till you see all that’s happening behind the scenes.


Step 1: Getting ready for departure

You just pressed “Send” – your work is done. Now it’s the ESP’s turn to get to work. During this first step, the ESP (Mailjet, that is) prepares your Christmas campaign for sending by completing a series of steps. First, if you have used any personalization in your email, like using dynamic subject lines that include your contact’s first name or other demographical data, this information is applied. The email is also provided with a digital signature so the receiving server can verify the domain (DKIM). Then, the ESP converts your email into two sections: the header and the body.


Before your email can leave Mailjet, it has to go through various processes where it will be formatted, checked and passed. But what is checked, specifically? Well, pretty much everything. Mailjet’s MTA (Mail Transfer Agent, the software that transfers emails from one computer to another) looks out for potential spam or malware, and assesses everything from the length of your message to the words and characters used.

Finally, the ESP adjusts the delivery speed to fit each ISP’s own speed. The ISP is the Internet Service Provider you’re trying to send your emails to. For example, Gmail, Hotmail or Yahoo! Some ISPs accept larger volumes of emails in a short time span than others, so the ESPs send your campaigns at different speeds, breaking the total emails you want to send into different chunks to optimize your sending.


Step 2: Knocking on the ISP’s door

Once your email campaign is approved by your ESP (Mailjet, of course), your email is ready to step outside, walk into the wild, unknown territory that is the digital spectrum and make its way to the receiver. Your ESPs MTA (reminder: that is, the software Mailjet uses to transfer your email to another computer) now checks if the destination you’re trying to send to exists, by looking at the Domain Name System (DNS). If everything is correct, your ESPs MTA sends your email campaign to the MTA of your contact’s email server.


The email has been sent to the recipient’s mail server, your subscriber’s ISP. But before it is even accepted, the ISP’s MTA checks some of the information coming from the ESP. One of the main things ISPs investigate is your sender reputation. As with everything in life, reputation determines how successful you’ll be with your email strategy. Think of it as going to a club: if you’ve caused trouble there before, got into a fight or not paid your bill, you’re not going to get in. Same will happen if you’re not following the dress code, for example.

It’s the same with emails. A bad sender reputation will negatively affect your deliverability (that is, your ability to successfully deliver emails to the recipient’s inbox). The ISPs you’re trying to send to may block your email, so having a positive reputation is key to mastering email deliverability. You might even get blacklisted, which means you’ve been labelled as a spammer and your campaigns might have a harder time reaching the inbox.

Aside from your reputation, ISPs check a number of other elements to establish whether they should let your emails in or not. They try to figure out if the ESP is known and if the sender authentication (SPF and DKIM) is in order. ISPs also look into the metadata, format and structure of the email to ensure they are correct (the HTML code) and check whether the recipient inbox exists and isn’t full.

If your email doesn’t pass these checks, or if the email address you’re trying to reach simply doesn’t exist, it gets bounced. A hard bounce would occur if the ISP has determined the email address you’re trying to reach does not exist or is no longer active. If it fails any other checks, then it results in a soft bounce. And that’s not it. Depending on what checks your email has actually failed, the kind of soft bounce you get could be different. It might get a temporary bounce telling you to re-attempt the message because they might be willing to deliver it later. Or your Christmas campaign might get rejected (and your future sendings too), which would mean the ISP is not willing to let your emails through until you improve your practices and your reputation.


Step 3: Landing safely

But your campaign is awesome and it has passed all the checks and convinced the ISP to finally open its doors. Yay!

Now it’s the ISPs turn to look into the actual email. Basically, the ISP will make the content go through some internal spam filters and assess your sender reputation against its own reputation list.

When an email fails these requirements, it will be sent straight to the Mordor of the emailing world, the junk folder. If you’re lucky, your campaign will be spotted there, but we wouldn’t put our money on this. And even if it does get noticed, having your emails land in the spam folder doesn’t give the best first impression.

If your email manages to pass this very last obstacle, then it will be allowed to land safely in the inbox, along with many other emails fighting for your contact’s attention. Some ISPs, like Gmail, even have different folders within their inbox. Now it is up to the title, design and content of your email to shine and really grab the reader’s attention.


The inbox folders in Gmail

At last, the journey of your email is finally over. Yeah, we know, looking back, Santa’s journey around the globe to deliver the Christmas presents pales in comparison. But all of these intermediate steps and security measures are necessary to ensure that no harmful messages reach the inbox. And actually, what looks like a long and eventful journey could really just be a matter of seconds.

How much did you know about the journey of your emails through the Internet? Tell us all about it or tweet us your questions using the hashtag #MailjetDelivers.

Yahoo!’s Security Breach And What It Means For Your Email Sending

Last week, the Internet was shaken by another scandal on data security. Yahoo! announced that the credentials of 500 million of their user accounts had been stolen back in 2014. We know you heard about this and have a million questions. Worry not, Mailjet’s here to make sure you know exactly what’s going on, how it may impact you as a sender and to help you tackle the consequences.

Wait, what happened?

On September 22nd, Yahoo! published an important message on their user security. It revealed a massive security breach going back to 2014. The credentials of 500 million Yahoo account users were stolen and had been put up for sale by a hacker (allegedly, the same hacker who had been involved in the Linkedin and Tumblr’s security scandals). 

According to Yahoo!’s announcement, the data that had been stolen included:

  • Names,
  • Email addresses,
  • Hashed passwords,
  • Telephone numbers,
  • Dates of birth,
  • Security questions and answers.

Bank account data and protected passwords don’t seem to be among the stolen data, according to the investigation that is still ongoing.

Potentially affected users have been contacted by Yahoo! and all users are strongly recommended to change their passwords if they still use the same one as they had in 2014.


Does This Impact Me As A Sender?

Such a massive leak is likely to have a lot of consequences, and yes, it could have an impact on you. More precisely, it could have an impact on your deliverability.

Some Email Service Providers have already started reporting a high hard bounce rate linked to Yahoo! accounts. This may be related to Yahoo! deactivating accounts that would have been operated by the hackers who got access.

It is also likely that at least part of Yahoo! users might feel that their data isn’t secure anymore with that address. Imagine that your name, the keys to your place and your address had been out in the open for a year and a half. Some people will just change their lock, but others might even desert their house and move to a new one… Which means that a lot of people might give up their email IDs, close their accounts and move to new ones, resulting in a high number of hard bounces for your campaigns.


Nope, this isn’t the hard bounce we’re talking about.

Nope, this isn’t the hard bounce we’re talking about. 

Hard bounces are responses received from Yahoo! indicating the sender has sent to an invalid or inactive address. Hard bounce rates are part of the criteria Internet Service Providers use to gauge the quality of a sender’s list and reputation, so having a high hard bounce rate could potentially cause a negative effect on your deliverability.

Now you could be wondering: “If the issue is known, ISPs should be more flexible and raise their threshold when it comes to defining a bad level of hard bounce, right?”. Unfortunately, it’s not that easy. These filters are operated by complex algorithms hunting phish and fraud, not by real humans. They track your metrics as a sender against what they deem to be “normal” for most legitimate senders.

So here’s what’s likely to happen:

  • If your hard bounce rate raises just a little, but the rest of your metrics are still OK and you’ve had good statistics, the impact will be minimal – perhaps just a few cases of emails landing in the junk folder.
  • If your hard bounce rate raises a lot, it might result in a lot of messages going to the junk folder while it remains high, and maybe for a few days after your rates are back to normal;
  • If you see a peak in your bounce rate, you may see some messages rejected, blocked temporarily by ISPs for several hours, or even several days.

What Can I Do To Limit The Damage?

In order to protect your sender’s reputation, we recommend that you monitor your bounce rate very closely. At Mailjet, we have a 8% bounce threshold within our sending policySo make sure you keep an eye on it, as anything higher may result in a rate limitation.

We recommend that you remove all the bounce addresses from your contact list after each campaign that you send during the next few weeks. It might seem slightly painful, but it is definitely the quickest and safest way to get your bounce rate back to normal and limit the damage on your deliverability.



If you want to address the Yahoo users who could be tempted to close their account but haven’t done it yet, you could create a segmented list that targets those with Yahoo contacts that have been “active” during the the last three to six months (those who opened/clicked in your recent campaigns). Send a specific campaign to offer them to update their preferences and give them a chance to provide a new email address to proactively ensure that your mail follows them to their new address.


Have you noticed any impact on your latest email campaigns following the Yahoo! security breach announcement? How do you plan to tackle it? Tell us more on Twitter.

It’s Time To Give Up Webmail Addresses To Send Emails Through An ESP

As consumers, we all have at least one free webmail address – when not several for the geekiest of us. Webmail providers like Gmail, Yahoo, AOL, Orange or Outlook are a convenient and powerful way to get a personal email address. A lot of users are even so fond of their webmail address that they sign up for Mailjet using it, rather than a corporate one!

One of the biggest threats when it comes to email, and especially for webmail, is Spam. These providers were at the forefront of this fight, providing users with advanced spam filters to lower the number of unsolicited emails or phishing attempts. While the spam volume decreased in 2015, it’s still high and email industry leaders, including Mailjet, are hard at work to make email a safer medium.

The email community battle against spam

One method to improve your email delivery rates is to incorporate SPF (Sender Policy Framework), and DKIM (Domain Keys Identified Mail), into your DNS settings. With this addition to your DNS entries, you’re telling recipients that you’ve authorized Mailjet to send emails on your behalf.

To further protect your brand from phishing attempts, DMARC (Domain-based Message Authentication, Reporting & Conformance) can be implemented in conjunction with SPF and DKIM.

DMARC is a policy that tells the recipient servers how to react if they receive an email that appears to be sent by you or any “” address, when it’s actually not. You can set your DMARC policy to simply monitor the mail being sent using your domain, or you can tell mailbox providers to quarantine it to the spam folder, or reject unauthenticated emails completely.

Yahoo and AOL already implemented a strict DMARC policy (that asks to reject non-identified emails) back in April 2014. Yahoo extended this on 62 ADDITIONAL domains recently, and Google announced that it will do the same later in the year with


What does it mean for Mailjet users?

In other words, if you are using Mailjet to send out emails with a Yahoo email address, or a Gmail one after June 2016, it will bounce – it will be rejected and not even make it to the spam folder. Your recipient’s email server will detect that it is not coming from a legitimate Yahoo or Gmail email server and will refuse it – it’s not even gonna make it to the spam folder. In the near future we expect inbox providers to begin filtering senders that don’t have a DMARC policy protecting their domain. You will not regret being ahead of the curve on this.

Since we have always recommended to use an email address on a customer-owned domain, few of our clients will be impacted by this change. But we want to use this occasion to re-emphasize on the fact that email is a serious aspect of your communication and should be done on domains that you own.


What to do to make sure your sendings are safe?

Head out to your account, in the Sender domain & addresses menu and make sure you don’t have a webmail email address registered in your email addresses list. If you do so, we advise you to make sure it is not in use.

If you do not own an email with your own domain, we strongly advise you to register your own domain, create an email address on this domain, publish your SPF and DKIM records and add this domain and address in your sender domains and addresses list.

We are also working on an alternative solution to enable new users, low-IT resourced clients and infrequent senders to continue sending without going through the hurdle of managing their own domains, and will introduce it pretty soon.


In the meantime, feel free to contact our support team if you need more guidance – we’ll help you make sure the transition to your own sending domain is as smooth as possible.