Deliverability : The purpose of deliverability is to ensure that your emails arrive in their intended inboxes, as opposed to be-ing marked as spam.
Previously, deliverability consisted mainly in applying the basic rules of emailing relating to content (text, images, html code…) Today, the main factors also taken into account are the quality of
Preamble
In your opinion, how many criteria influence deliverability? 10? 20? Actually, there are even more! In this checklist, we have identified 34 factors that can impact the deliverability of your emails…
No complicated explanations, just a quick and easy to understand guide…and if you would like to learn more, check out our blog: https://www.mailjet.com/blog
Adopt a dedicated IP address?
Don’t forget to “warm up” your IP address (in case of a dedicated IP address) Should you separate transactional and marketing email?
Use a domain name linked to an existing website Take advantage of email throttling
Configure abuse@ and postmaster@ email addresses Consider Return Path Certification
Consider using “seedlists” Monitor blacklists
Monitor spam complaints and use feedback loops Adopt an obvious and immediate unsubscribe process Manage your errors (bounces)
Do not buy or exchange email addresses Use a double opt-in procedure
Send email campaigns regularly Delete inactive addresses DATA QUALITY
Create multipart emails (HTML + Text version) Avoid image-only emails
Delete words frequently used by spammers
Make the sender clearly identifiable
Observe good HTML practices View your email rendering
Test your content in different spam filters
Use pre-headers
Do not use links that contain an IP address EMAIL CONTENT
OTHER BEST PRACTICES
8 9 10 11 12 13 14 15 16 18 19 20 21 22 23 24 26 27 28 29 30 31 32 33 34
The technical part is the most complicated aspect of deliverability, but don’t worry, it also happens to be Mailjet’s specialty!
Don’t hesitate to ask for our help: our teams are ready to respond to all your questions.
• Authenticate your emails • Use a public Whois
• Pay attention to forward and reverse DNS lookup • Adopt a dedicated IP address?
• Don’t forget to “warm up” your IP address (in case of a dedi-cated IP address)
• Should you separate transactional and marketing email? • Use a domain name linked to an existing website • Take advantage of email throttling
• Configure abuse@ and postmaster@ email addresses • Consider Return Path Certification
• Consider using “seedlists” • Monitor blacklists
The Mailjet perspective:
If you already have a Mailjet account, log onto our website and use our Assistant to configure your SPF and DKIM. If not, you can sign up here.
1. Authenticate your emails
By authenticating your domain, your recipients will not see the sent “via” text (see image below) and your domain name reputa-tion will be improved.
SPF : This oldest authentication method adds the IP addresses allowed to send email via your domain name in your DNS record. DKIM : Also based on the DNS record, this authentication solu-tion is used to sign emails with a public or private key system. DMARC : This new technology allows the sender to check whether emails have been properly authenticated by the ISP or webmail.
The Mailjet perspective:
This is one of the first things verified by our team in case of problems. The need for a public WHOIS is fairly recent: previously, it only applied to large senders.
2. Use a public Whois
The “whois” lists the contact information related to a domain name. They include information on the owner, the technical con-tact and the host of your domain. Disclosed information includes: the full name, email address, postal address and telephone num-ber of each reference.
Some providers allow the option of hiding this information, or making the WHOIS Private. This practice is used by spammers and should be avoided at all costs.
The Mailjet perspective:
Our technical team can help you with these complicated configurations. Don’t hesitate to contact us if you need assistance!
To verify your identity, ISPs and webmail frequently use DNS (Domain Name System).
That is why it is important to properly configure these settings in the control panel of your web host account (if your host allows it). Reverse DNS lookup : verification of a domain name associated with an IP address;
Forward DNS lookup : verification of an IP address associated with a domain name.
The Mailjet perspective:
Mailjet’s IP addresses are closely monitored by our deliverability team, guaranteeing an excellent reputation. You can benefit from a dedicated IP address which are available on our “Silver” package.
The IP addresses used to identify the origin of emails routed through servers acquire a reputation (positive or negative), which is based on the quality of messages and interactions generated. Having a dedicated IP means that you don’t have to share the reputation of your IP with other users on your mailing platform. However, to acquire a good IP reputation takes time and regular sending volumes. It is therefore important to conduct a warm up period and send at least a few thousand emails per day.
Read more about it on the blog: how to monitor the reputation of your IP address
The Mailjet perspective:
By default, the warm up isn’t necessary because shared IP addresses on Mailjet already have a stable, trusting relationship with ISPs. If you opt for a dedicated IP, our teams will support you throughout the warm up period. In any case, automatic limits are applied to new accounts to avoid any incidents.
When you begin sending emails with a new IP address, it has no reputation and is not immediately trusted by ISPs & webmail providers.
In order to build up this trust, you must “warm up” your IP ad-dress by sending a consistent number of high quality emails every day for 3 to 4 weeks.
IP address (in case of a dedicated
IP address)
It is important to use different email addresses for marketing and transactional emails. By separating your various types of email, it will also separate potential delivery issues when they arise. Recently, intelligent inboxes, at Gmail and Outlook.com for exam-ple, have begun to automatically sort emails by category: Promo-tions, NotificaPromo-tions, and Social. In order to avoid your confirma-tion emails arriving in the Promoconfirma-tions category, it is important to separate your transactional and marketing messages.
Read more about it on the blog: Power Up Your Transactional Emails
6. Should you separate
transac-tional and marketing emails?
The Mailjet perspective:
With Mailjet, it’s possible to separate different types of emails via sub-accounts and manage the priority of outgoing emails. Do not hesitate to contact us to discuss your needs.
The Mailjet perspective:
You should use a sender address corresponding to a professional domain name that contains, at the minimum, a webpage describing your business, a privacy policy page and full contact information.
Verifying sender information is an essential element in the fight against spam.
Spammers don’t create websites for their sender domain, (i.e., free-viagra.biz). If your domain directs readers to an empty web-site page, how will ISPs react? They will automatically be suspi-cious of you.
7. Use a domain name linked to an
existing website
The Mailjet perspective:
Mailjet adjusts the sending speed and the number of simultaneous con-nections in real time in order to optimize the deliverability of your emails. You will also benefit from the experience of our deliverability team. This technique consists of adjusting the sending speed of emails/ campaigns in order to respect the rules established by the main ISPs.
The configuration of several different parameters will optimize your email deliverability:
- The number of emails sent per minute or hour - The number of connections per minute or hour - The number emails sent per connection
8. Take advantage of
“Email throttling”
The Mailjet perspective:
By default, Maljet manages these returns for the most popular ISPs that meet industry standards. But beware: if our abuse@mailjet.com address is solicited, our deliverability team will be alerted and your practices may be investigated or questions. Finally, note that these addresses are required for certain whitelisting procedures.
These are email addresses to receive consumer complaints (abuse@) and information on potential technical problems (post-master@).
If these addresses are not configured for your domain name, they can return an error to ISPs, indicating that you don’t pay attention to these messages. This is not good!
9. Configure abuse@ and
post-master@ email addresses
The Mailjet perspective:
Our privileged partnership with Return Path allows for rapid contact and collaboration. Contact us if you are interested.
Return Path offers certification for your IP address (a white list) that allows you to speed up the delivery of your emails to inboxes (for a limited list of ISPs and webmails).
Certification can also permit images to be displayed by default: your recipients will not have to click on the “display images” mes-sage.
The benefits are many, but this certification is only for large send-ers and can quickly become expensive.
10. Consider Return Path
certification
The Mailjet perspective:
Our interface does not offer access to Mailjet seedlists or their results. But in some cases, our deliverability team may propose to carry out these tests for you on a dedicated IP, during the warm up phase. By adding a sample of email addresses to your contact list, it is possible to verify that your emails are delivered.
Unless you go and check each of your contacts’ inboxes, it is difficult to know if your email arrived at its destination. This tech-nique involves creating a batch of “witness” email addresses to check if your email was properly received.
The Mailjet perspective:
Our deliverability team carries out preventative monitoring of different blacklists. We also have many contacts with ISPs and blacklists ser-vices, which facilitates the unblocking process, when it is necessary and There are many blacklists used by ISPs and webmails to filter incoming messages.
Often referred to as RBL or DNSBL, these lists are mostly gov-erned by independent anti-spam services. They usually block certain IP addresses or entire networks. In addition to being widely used by ISPs, the most serious blacklists are part of a consortium that actively communicates and shares information. Many services offer to verify whether your IP address and domain name are present on a blacklist. For example: Mxtoolbox.com or Blacklistalert.org.
Read more about it on the blog: 5 Ways To Avoid Landing On An ISP Blacklist.
• Monitor spam complaints and use feedback loops • Adopt an obvious and immediate unsubscribe process • Manage your errors (bounces)
• Do not buy or exchange email addresses • Use a double opt-in procedure
• Send email campaigns regularly • Delete inactive addresses
Deliverability largely depends on engaging recipients. Beyond content, data quality is of the utmost importance.
The Mailjet perspective:
Mailjet automatically generates feedback loops for larger ISPs. Reports of spam are displayed in your account and available via our APIs. The relevant contacts are automatically blocked.
Certain ISPs and webmails allow you to receive an alert when your email is flagged as spam, also known as a “feedback loop” (FBL).
It is important to record these complaints and remove associ-ated contacts from your lists. The mechanism involves indicating to ISPs that you want to be notified of spam messages reported against you in order to process them. This approach is not pos-sible for all ISPs and is usually done via a form directly found on their websites.
Read more about it on the blog: SPAM: the gift that no one wants
13. Monitor spam complaints and
use feedback loops
The Mailjet perspective:
If you use our online interface, the unsubscribe link and page are man-aged automatically. Through SMTP relay, you must manage this yourself, or add the tag “[[UNSUB_LINK_EN]]”.
An unsubscribe link is essential to avoid being classified as spam. The link to the unsubscribe page must be functional, instanta -neous and easy to find in the email.
Do not ask users to confirm their desire to unsubscribe and reas-sure them that you will no longer contact them. Otherwise, they will confirm this themselves by flagging you as spam and block-ing your sender address.
14. Offer a clear and instantaneous
unsubscribe option
The Mailjet perspective:
Mailjet’s deliverability optimization system processes these errors. When they are temporary, new attempts to send are made automatically. Only after a certain number of unsuccessful attempts will the email result in an “error” status. It is then automatically blocked for 90 days.
It is very important to address the emails that result in errors by deleting the offending addresses from your lists. Indeed, ISPs penalize high error rates because they often reflect poor practices (old lists, no double opt-in, etc.).
Permanently deleting addresses that bounce back with errors al-lows you to maintain a clean database, free of inactive or nonex-istent contacts.
Note that temporary errors, “Soft Bounces” (full mail box, auto-matic away message...), should not be cleaned immediately. Only “Hard Bounces,” or permanent errors, should be addressed right away.
Consult our documentation regarding email status.
The Mailjet perspective:
Buying or exchanging email addresses is against our anti-spam policy. Our system and deliverability team have the ability to detect it. If you participate in this practice, you risk having your accound closed, without notice and without a refund.
Lists of email addresses that circulate on the Internet have usually been copied many, many times. They are of very poor quality and are riddled with spam traps (fake addresses).
Only use contact lists that you control. Recipients must explicitly agree to be contacted (opt-in).
Avoid the so-called “tips” from friends, colleagues, and partners. You should especially be wary of sites specializing in the sale or rental of email databases. In addition to being discouraged by ISPs, this practice often results in lost money, along with the risk of blacklisting and this should be avoided at all costs.
To read: Mailjet’s anti-spam policy
16. Do not buy or exchange
con-tact lists
The Mailjet perspective:
If the double opt-in is not required from a legal standpoint, it is neverthe-less required by ISPs. At the very least, quickly identify errors gener-ated by subscription confirmation emails and use them to update your Double opt-in consists in validating the address via email, in order to verify that it does in fact exist and is in working order. This is a very effective way to increase the quality of addresses gathered. In addition to guaranteeing the existence of the address, you will also be able to verify that your contact is indeed its owner. This process consists of adding a confirmation link in the welcome email and to validate the address only once the link is clicked. Check out some of our plugins for your website, where you can add a sign up widget.
The Mailjet perspective:
Solicit your contacts at least once a month. If your list has not been used in the last 6 months, contact our support team before any sending. Oth-erwise, errors will cause a blockage or worse, blacklisting.
Never leave your email addresses alone for months at a time! Your contacts have memories almost as short as the lifespan of their email addresses (about 6 months).
Regularly send emails (example: a newsletter) to remind them of you. This approach is also beneficial for your brand.
Without regular mailings, some customers will forget they sub-scribed. Their reaction will then be to report you as spam!
18. Send campaigns regularly
The Mailjet perspective:
Unsubscribe all inactive addresses (no clicks or opens) over the past six months.
When a recipient does not respond to your emails for several months, this can mean several things. Either he does not use the email address in question anymore, or perhaps he is no longer interested in your offer. In either case, this is detrimental to your reputation. In the worst-case scenario, these inactive addresses can become spam traps.
The greater the number of inactive contacts, the more your repu-tation rate suffers, impacting…your deliverability. It is thus neces-sary to delete these addresses or create a special reengagement program.
Read more about it on the blog: How to avoid the pitfalls of inac-tive contacts?
• Create multipart emails (HTML + Text version) • Avoid image-only emails
• Delete words frequently used by spammers • Make the sender clearly identifiable
• Observe good HTML practices • View your email rendering
• Test your content in different spam filters • Use pre-headers
• Do not use links that contain an IP address
Certain tips described below allow you to more easily bypass anti-spam filters. Others serve to increase the quality of interactions generated by your emails, thus improving your reputation and deliverability.
The Mailjet perspective:
Our campaign design tool automatically generates a text version for you. If you are sending by other means (API, SMTP...), do not forget to create a text version and be sure to check the content generated.
Make sure your emails are composed of two parts, one in HTML and one in text format.
The text version of your emails remains indispensable. Certain email clients do not yet display HTML on mobile devices and anti-spam filters compare the content of text and HTML versions to ensure that they are similar.
20. Create multipart emails
(HTML + text version)
The Mailjet perspective:
Images should not exceed 25% of the surface of your emails. In addi-tion, they should not contain any text.
Spammers have a habit of hiding the text of their emails in images to avoid spam filters. As a result, these filters have learned to be wary of images.
Images should only be used as decoration and should never replace text.
Read more about it on the blog: Avoid image-only emails
21. Avoid image-only emails
The Mailjet perspective:
Exercise caution! Patiently reread your content and find clever turns of phrase to spark the interest and curiosity of your recipients, without us-ing problematic words.
Talking about little blue pills or a certain famous brand of Swiss watches in your emails is not a great idea, as you undoubtedly know by now.
But there are many other words that suggest spam/phishing, and their use should be limited.
Examples of words that are less obvious than “Viagra” or “Rolex” but should be avoided in excess: “Free, ””Credit,” “Pharmacy,” “Sale,” “Promotion,” “Click here,” “Urgent,” etc.
Check out our post on: Words That Will Trip The Spam Alarm
22. Delete words frequently
The Mailjet perspective:
We even recommend that you always mention your brand /domain name in the subject line. This practice is welcomed by recipients and anti-spam filters alike (because it shows them that you are not trying to hide anything).
It is crucial that your subscribers recognize your emails at first glance. Otherwise, the chance of your email being marked as spam is higher.
The easiest way to identify yourself is to use the name of your brand or site in your sender name.
23. Make sure the sender is clearly
identifiable
It is sometimes time-consuming and daunting to code your HTML emails (using tables, online CSS...). However, spam filters attach great importance to the quality of your code.
Do not forget to close your tags, write the HTML code in lower-case, add alternative attributes of your images ... In short, follow the rules!
The Mailjet perspective:
If you are not an expert in HTML, use our WYSIWYG editor: the code will be self-generated and automatically optimized!
The Mailjet perspective:
Don’t rely on fancy design or anything too complicated. Emphasize content and follow the standards, as old as they may be. When in doubt, use one of the many testing tools available on the market (Litmus, Return Path...).
To ensure a maximum level of interactions, it is necessary that your designs are perfect! As each email client has its bugs and display tips, it is essential to test reports on several of them. Gmail does not support <style> tags ... </ style>, Outlook does not handle background images and CSS3 is still supported by very few.... There are many peculiarities.
On the client side, test on the most popular providers: Apple Mail, Thunderbird and Outlook. On the webmail side, do the same: Outlook.com, Gmail and Yahoo!Mail are a good starting point. Also, don’t forget mobile devices: iPhone, Android, etc.
The Mailjet perspective:
Tools like Litmus and Return Path let you test your emails in different spam filters. In the Mailjet interface, a SpamAssassin score is displayed in reports. Feel free to send a campaign to test addresses to verify it. Each spam filter reacts differently to the content of your emails. This is why it is important to be careful and test each of them. SpamAssassin is the best known and most widely used spam fil-ter and there are dozens of others out there. For example: VadeR-etro, Cloudmark, Barracuda, Postini... not to mention the various filters of email clients (Outlook, Thunderbird...) and webmails.
26. Test your content in different
anti-spam filters
The Mailjet perspective:
Take the opportunity to use this space to include a tagline or a comple-mentary introduction to your topic. Our online tools allow you to do this in 2 clicks.
Some interfaces display the first few lines of the message just below the object. This is a space to be utilized and used to your advantage.
Too often, the user see the familiar useless pre-headers: “See the online version”, “click here to see..” or “if you do not see....” What a waste! Even the recipients who do not open the email read these lines.
Read more about it on the blog: tips on optimizing your newslet-ters for mobile.
The Mailjet perspective:
We automatically offer tracking links to detect openings and clicks on the r.mailjet.com domain. But also know that it is possible to modify these links for the benefit of addresses corresponding to your domain Carefully avoid the links generated by advertising or URL shorten -ers. Also, do not use IP addresses as links!
These mechanisms are often used by spammers to conceal land-ing pages. Identification is one of the keys to deliverability; it is essential that the links used in your emails reflect the identity of the landing page.
28. Links: Avoid IP addresses, link
shorteners...
• Avoid “noreply” addresses • Segment to increase reactivity • Obey the law
• Be consistent with the promises made at the time of sub-scription
• Provide a link to the privacy policy in your emails and on your website
• Invite your subscribers to add you to their address book Whether obvious or not, these little tips are good to remember and could make all the difference for your deliverability.
Here’s a quick crash course on how to Segment and Personalise using Mailjet:
A sender address should always be able to receive emails. Take care of your contacts and do not cut off the conversation with a “noreply@yourdomain.com” address. You would be much better off with “yesreply@yourdomain.com”!
In case of questions, comments, or problems related to an email, the reply button is naturally very often used because it is so ac-cessible.
Isn’t it illogical to invest in social media and then cut the conver-sation via email short? In terms of customer relations, “noreply@” makes no sense.
29. Avoid “noreply” addresses
The Mailjet perspective:
Why not use an address linked to your customer service or your Commu-nity Manager? This will humanize the communication.
The Mailjet perspective:
Consider using a CRM and/or offer subscriptions tailored to your con-tacts. See how you can Segment your data with Mailjet.
All of your recipients have different needs and expectations. Classify your contacts by their affinities, how they use your ser-vices, or better, offer personalized subscription options (subject, frequency…).
30. Segment in order to increase
reactivity
The Mailjet perspective:
If you respect your subscribers, chances are that you are also obeying the law. Mailjet requires opt-in and opt-out procedures. Privacy and data security is a priority for our teams. With servers in Europe, Mailjet users are not affected by PRISM.
Legislation on respect of privacy is different in almost every coun-try. It is important to educate yourself.
You also have responsibilities to protect the privacy of your us-ers. Storage of their personal information should be secure and sometimes even authorized by the user himself. Check the valid-ity of your registration process, conditions of use and your legal disclaimer.
The Mailjet perspective:
If the rules change, ask for permission again or offer an alternative to avoid irritating your contact.
Obtaining the email address of your contact does not give you the right to do whatever you want. Do not excessively contact your users; you should respect their habits and the reason why they signed up in the first place, or else they may use the spam button against you.
If you promised one newsletter per month, there is no question of changing the rules along the way…warn your users and give them the opportunity to change their preferences.
32. Be consistent with the
prom-ised you made at the time of
sub-scription
The Mailjet perspective:
In the header or footer of your email, remind your contacts how you got their address and why you are contacting them.
This is a crucial factor in gaining your subscribers’ trust, but it is also important for ISPs and webmails, in case of an unblocking request.
Be as reassuring as possible about your practices and your respect for your subscribers. Create a privacy policy web page on the subject that will also contains your contact information. Providing a phone number is often a plus.
33. Provide a link to your privacy
policy
The Mailjet perspective:
Use your welcome emails and/or your subscription confirmation page to encourage your subscribers to add you to their address books.
This will allow you to easily send emails to the recipient’s inbox. This is a positive for anti-spam filters.
In your communications, it is rare to find a message from a friend, parent, or colleague in your unwanted mail. This is simply be-cause one or several exchanges have already taken place and each party has the other in his list of contacts.
34. Invite your subscribers to add
you to their address books
Mailjet is an all-in-one solution to create, send and report, both marketing and transactional emails. Our technology is cloud-based, highly scalable with proprietary technology that optimizes email deliverability. Mailjet can be accessed via an easy-to-use online drag-and-drop interface, through APIs that allow developers to integrate its array of features within their applications or send through its sophisticated SMTP relay.
Founded in 2010, Mailjet is now an international leader within the Email Service Provider space, with more than 60% of revenues generated outside of its native France. To date we have processed over 12 billion emails for nearly 200 thousand customers around the globe; and our team has expanded within 5 countries in 3 continents. You can pay us a visit at our local offices in Paris, Berlin, New York, London, Ho Chi Minh City and Toronto. At Mailjet we believe in honest deliverability and dedicate
substantial amount of our resources to innovation, as well as fighting the war against SPAM. This is to provide a seamless service, high deliverability and a next generation emailing platform with 99.998% uptime for our customers. We can do this, because Mailjet is built from the ground up.
Be sure to check our blog regularly for how-to guides, posts on optimizing your emails, the latest digital marketing strategies, and occasionally just to hear about our awesome adventures!
Jonathan Loriaux is an email marketing consultant and the author of the blog www.badsender.com (in French). He assists Mailjet in developing content around the themes of deliverability, transactional email, and email marketing at large.
