You’ve spent time building a targeted email list. Your creative team has drafted an awesome email.
Making sure your emails actually get delivered.
If an email ends up in the junk folder, then did it ever even exist? For your customer, the answer is no.
But don’t worry.
In this guide we’re going to deep dive into email deliverability. And we’re going to show you how to keep your emails away from the dreaded spam folder.
Ready to up your open rate and get more clicks to your website? Let’s get started.
Here’s our Table of Contents:
- What Is Email Deliverability? – a quick definition to be sure we’re on the same page.
- In a Rush? The Email Deliverability Infographic
- 1st part: How Email Reputation Impacts Deliverability
- 2nd part: Why Authentication (DKIM, SPF AND TLS) Is Critical To Email Deliverability
- 3rd part: How Infrastructure Impacts Email Deliverability
- 4th part: How Content Affects Email Deliverability
- 5th part: Other Factors Affecting Email Deliverability
- So, what do you need to be doing to boost your email deliverability?
So, what do you need to be doing to boost your email deliverability?
First, the facts:
What Is Email Deliverability?
Email Deliverability is the set of processes responsible for placing an email into your client’s inbox. Inbox placement and delivery is a complex subject. Many factors are taken into account by mailbox providers before placing an email into your subscribers’ inbox.
So what are those factors? Let’s dig into into the detail.
In a Rush? The Email Deliverability Infographic
We have put together all the factors affecting email deliverability in a handy infographic. Discover how you could improve your open rates.
Part 1: How Email Reputation Impacts Deliverability
When you send an email campaign, mailbox providers run an initial set of vetting checks.
These are known as reputation checks. A bit like credit checks for email, they are affected by:
- Sender reputation
- Server / IP reputation used to dispatch the email
- Domain reputation of links in the content
- Email engagement metrics. These include bounce and spam complaint rates for your sender, domain and server
Reputation checks are one of the most important factors of inbox placement.
A subpar reputation will see your inbox placement and open rates tank.
Let’s look at all the factors that are bound to email delivery reputation. We’ll start with sender reputation.
What Is Sender Reputation?
Sender reputation is the reputation of the email address you are using to send out your email campaigns.
But how exactly does sender reputation work? What factors increase or decrease your sender reputation?
Email Deliverability goes hand in hand with sender reputation. Here’s 5 factors positively influencing sender reputation: consistent volume of email campaigns per week, few bounces, fewer complaints, no spam traps, no black lists. #checklist
Let’s find out.
1. Be Consistent With Your Volume
Try to evenly distribute your email marketing campaigns.
A consistent volume of email campaigns, without major drops or spikes, plays a significant role in sender reputation.
For example, if you send out an email to your list twice a week, switching to three times a week, will cause ripples.
There will be times when you will want to send out more emails than normal. For example over the busy Christmas period. But aim for a regular, consistent schedule where possible.
Your list will soon get to know your schedule, which will help to increase open rates and click throughs.
2. Keep Your Lists Clean To Crush Bounce Rate
Clean your lists.
At Moosend we use NeverBounce, Data Validation, and Email List Verify, among others.
Bounces are emails that fail to reach the subscriber.
Notwithstanding their impact on future deliverability, they are a waste of resource.
There are 2 types of bounce, soft and hard.
What is Hard Bounce?
A hard bounce happens when you send a message to a mailbox that doesn’t exist. Perhaps someone used a fake email to sign up to your list, or have changed email provider.
Either way, you don’t want those email addresses on your list.
What is Soft Bounce?
A soft bounce occurs when you send to a:
- mailbox that is full
- recipient with an auto-reply / out-of-office message
You probably don’t want to remove these email addresses from your list. Normally this will be a temporary issue. But if your messages are consistently bouncing you might want to reconsider.
Mailbox providers, such as Gmail, monitor the bounce messages. They then return undelivered emails back to the email service provider.
A high bounce rate implies a subpar list hygiene process. That could mean a list that is not contacted frequently or is purchased.
Lists with high bounce rate are often classified as spam by mailbox providers.
3. Spam Complaints = Death For Your List
When your subscribers hit the dreaded “Mark as spam” button, mailbox providers like Gmail, and ESPs like Moosend receive a notification.
The bad news?
Even senders with a small number of complaints are automatically blocked by mailbox providers.
It’s for this reason that we strongly discourage the use of purchased lists. They will see your spam complaints rocket.
4. Steer Clear Of Spam Traps
What’s a spam trap?
It’s a fake email address. And it’s used to catch out unscrupulous marketers who have been harvesting emails.
They’re like honeypots that are published in a hidden location in the web.
When spammers collect email addresses through harvester programs, or through purchased email lists, these fake email addresses often make it onto their lists.
Sending even a tiny amount of emails to those email addresses automatically marks the sender as a spammer. It’s clear that they built their list unnaturally.
5. Whatever You Do, Don’t Get Blacklisted!
Black lists are lists of sender domains (e.g. yourdomain.com) and servers, or IP addresses that have been caught sending email spam.
Send an email from a blacklisted server or domain and the chances are it will land in junk (or not at all).
There are over 100 black lists for different purposes and you need to stay off of every single one of them.
So what gets you blacklisted?
Falling foul of any of points 1-4 above.
The good news is that if you get blacklisted once, there’s a strong chance you will be able to de-list your site/server. Repeat offenders will have more trouble getting off the blacklist.
Moosend monitors black lists and keeps users safe.
You can use mxtoolbox to check to check if your server or domain is blacklisted.
Part 2: Why Authentication (DKIM, SPF AND TLS) Is Critical To Email Deliverability
As you’ve probably gathered by now, email deliverability is a complex topic. But it’s also an evolving one.
Spammers are always looking for new loophole and tricks. New ways to abuse your email inbox.
On the flip side, mailbox providers like Gmail are catching up in keeping spam messages low, or out of sight altogether.
But now let’s look at a tactic that has been used by spammers for years: email sender spoofing.
How Spammers Use Email Sender Spoofing
Sending an email on behalf of someone like email@example.com is easy. Change a few header values and the ISP will think that Mark is trying to send a message out.
Which means that spammers can easily impersonate your brand’s email and send campaigns on your behalf. Right?
Well, fortunately, it’s not quite as simple as that. And mailbox providers are getting better at catching this type of spam.
Most providers – certainly all major ones – will perform an ID check when receiving a new email.
Here’s how it works:
A mailbox provider receives an email from an address (say firstname.lastname@example.org)
The provider checks the IP address where the message originated
They then check to see if that IP address has permission to send emails on behalf of yourdomain.com
This is called authentication.
But let’s clarify something:
Sending emails on behalf of another address is not necessarily a bad thing.
Because this is exactly what all email service providers (ESPs) such as Moosend do to deliver the campaigns you design and send.
After all, you want to be sending email from your branded domain.
Setting up authentication in your email marketing service of choice is highly recommended. It will hint to Hotmail, Gmail and all other providers that you have given consent to send emails on your behalf.
There are two main ways to setup email authentication: SPF and DKIM.
Let’s take a look at them
SPF and DKIM are an item. In fact, they are complementary. What SPF lacks in ownership authentication, DKIM makes up for it in email validation.
6. Use SPF To Verify Your Sender IP
Setting up your SPF records is essential. On Moosend, it is intuitive, too.
SPF (Sender Policy Framework) is an email validation system designed to prevent spam by verifying the sender’s IP address.
An SPF record allows web administrators to designate which web hosts are authorized to send messages from a given domain.
So how does this work?
When an SPF record is added to your website’s DNS, servers use it to verify that you are allowed to send emails from email@example.com.
Simply put, SPF says you are the owner of the domain and are allowed to contact people using this domain name.
7. Use DKIM To Verify Ownership Of An Email Message
DKIM (DomainKeys Identified Mail) indicates ownership of the email message by a particular organization.
While the message is still in transit to the recipient, the organization’s signature is added to the email headers.
Most email clients will check for a valid DKIM signature on incoming email to identify who sent it.
Which means DKIM is a working way to increase email deliverability and your sender reputation with email services.
The receiving mail server can identify the origin of the email marketing campaign.
Should You Use SPF or DKM?
You should use both.
Unless you are an email marketing nerd, you probably don’t need to know exactly how SPF and DKIM work.
But what you do need to know is that both authentication levers are needed to reduce spam and improve email deliverability rates. SPF and DKIM work together.
For instance, DKIM alone does not guarantee that the sender’s server is permitted to send outgoing email in the name of your website (your domain).
While SPF is powerless on its own because most websites use shared hosting. So many sites can share the same IP.
Where Are SPF and DKIM Records Located?
SPF/DKIM records are set in the “DNS settings” section of your domain name provider.
If you are wondering what DNS or Domain Name Service (or System) is, here’s a useful analogy.
Think of DNS as a phone book for the Internet. It translates human-friendly computer hostnames into IP addresses.
To make the authentication process easier for you, we have put together a list of Help Articles.
Find out more on how to set up SPF/DKIM depending on where you have registered your domain name.
How Do You Setup SPF / DKIM On The Moosend Platform?
Moosenders can easily set SPF/DKIM authentication by following the steps described in these Help Articles:
- What is SPF?
- What is DKIM?
You’ll learn exactly where SPF / DKIM settings are located in your Moosend account.
And you will also find out more about how to go through the authentication process correctly
The good news?
It’s super easy. In fact, it will only take a couple of minutes to set everything up.
And once everything is in place you should see an increase in the deliverability of your campaigns.
But if you’re struggling, don’t worry. Our friendly support team can answer any question you might have via live chat.
Will SPF / DKIM Guarantee That You Pass Anti Spam Checks?
Here’s the thing:
SPF / DKIM authentication is not a magic bullet for passing spam filters.
It’s an essential step in the process of increasing deliverability. But, inbox placement cannot be guaranteed by SPF / DKIM alone.
Need a more thorough explanation of why some emails reach the inbox, while others are marked as potential spam or junk?
How Can You Check That SPF / DKIM Are Properly Configured?
If you have updated DNS records correctly and SPF/DKIM authentication is not working right away, you might need to wait up to 24 hours.
Because it can take time for servers to read the change in your DNS records.
If you are still experiencing problems, you will need to contact your domain provider for tips on troubleshooting DNS records in their “DNS settings”.
Finally, here is a helpful resource on how to check if everything is set right.
8. Encrypt Your Email (Using TLS) To Build Trust With Users And Mailbox Providers
Moosend enables quick TLS setup – you no longer have to worry about service penalties!
By its nature, email is prone to information disclosure. Since most emails are transmitted in an un-encrypted form, TLS is essential.
So what is TLS?
TLS is a form of encryption for email messages which protects the content from being read by entities other than the intended recipients.
Email encryption may also be considered as a form of authentication.
Gmail implements TLS for email delivery, but at the moment it’s still an optional requirement. And there is still no proof that unencrypted emails fail inbox placement on Gmail or other providers.
Nevertheless, we believe that the TLS requirement will eventually become mandatory.
For the time being, TLS-enabled emails will show a nice padlock icon on Gmail to notify your customers that your emails are encrypted.
Part 3: How Infrastructure Impacts Email Deliverability
Email deliverability infrastructure is the software and hardware used to deliver your emails to your recipients.
The infrastructure required to send emails at scale is not to be taken lightly.
Setting up your own infrastructure rather than using an ESP such as Moosend is very complex, and cost-inefficient.
There are several low-level protocols and standards that you must implement and adhere to. And you will quickly find that you need very specialized personnel to handle the operation.
Franky, it just isn’t worth the hassle
And we strongly suggest that you use an ESP such as Moosend to handle tasks and focus on your core business.
So what exactly affects email deliverability from an infrastructure standpoint?
The IP Address (Dedicated vs Shared)
There are two types of IP addresses that relate to email deliverability.
Dedicated IPs, which are best practice for high volume senders, and shared IPs.
So which do you need?
9. High Volume Sender? Opt For A Dedicated IP Address
Dedicated IPs are exclusively used for your campaigns and senders.
Email programs based on dedicated IPs flourish on consistent, healthy volume.
Inconsistent volume, with dips and spikes, from a dedicated IP will be counterproductive and will classify you as a spammer.
10.Time Sensitive Campaigns? You Need A Dedicated IP Address
Dedicated IPs are used exclusively for your own campaigns.
There are no noisy neighbors or throttling because of issues caused by other senders.
It’s a direct connection to the ISP and lightning-fast at delivering your messages over to your recipients.
If there is any time-sensitivity in your campaigns we recommend that you opt for a dedicated IP.
Can I Get A Dedicated IP Address For Sending Emails At Moosend?
At Moosend we offer dedicated IPs to high-volume senders.
In fact, you don’t even have to worry about this.
We monitor your email marketing program and will switch you to a dedicated IP if we think it will benefit you and your subscribers.
But we also evaluate explicit requests for dedicated IPs as they are a scarce resource regionally and globally.
Additionally, requests for dedicated IPs often come from hardcore spammers. So all requests are vetted manually by our deliverability team.
11. Shared IPs For Everyone Else
Get a shared IP pool with Moosend – the ESP that has your back.
If you send fewer than 200-300,000 emails per campaign, then you don’t need a dedicated IP.
Your email marketing program would benefit more from using a shared pool of IP addresses.S
hared IPs are only available in Email Service Providers such as Moosend. You can’t create a shared pool of IP addresses for your own email marketing program.
Also, if you have concerns about your list hygiene or the quality of your mailing list you will be better served using a shared pool of IPs.
They will help you get a lift on your email deliverability if you are below average on the IP pool.
At Moosend, we have a range of shared IP pools that we assign to clients automatically based on:
- their overall quality score
- the engagement of their subscribers
- the industry they operate in
12. Monitor Mailbox Provider Feedback Loops
You must process feedback loops regularly – Moosend does this for you consistently!
Most major mailbox providers operate a feedback loop service to report back complaints to email service providers such as Moosend.
When one of your subscribers hits the “Mark as spam” button, a request makes it back to the ESP through the feedback loop.
It’s imperative to unsubscribe and remove customers who complained from your mailing list immediately.
The only way to do that is through monitoring various mailbox provider feedback loops.
At the time of writing, there are more than 20 major providers offering feedback loops. So implementation is not straightforward.
Fortunately, Moosend automatically registers all customers, senders and campaigns with feedback loops. We then report back on complaints received.
So, the hard part is over!
Some feedback loops, like the one offered by Gmail, are only available to exclusive members of M3AAWG (Messaging, Malware, and Mobile Anti-Abuse Working Group).
The good news?
Moosend is a member of M3AAWG and implement the Gmail feedback loop for your campaigns.
13. Set up (And Monitor) An Abuse Reporting Mailbox
Some mailbox providers require email campaigns that land in their users’ inbox to operate an abuse-reporting mailbox.
What is it?
An email address to forward abuse complaints to.
It’s important for deliverability that you have an abuse reporting mailbox setup and monitor it frequently. You can implement it through the use of an email header.
Many mailbox providers without feedback loops will forward complaints to those mailboxes instead.
14. Set up MX Records For Your Sender Domain
You need to have a valid MX record setup for your sender domain.
Because otherwise some ISPs will automatically block your email
Bonus: How To Check Email Sender Reputation
We have put together a comprehensive list of 10 online tools you can use to check email sender reputation for your domain name.
Part 4: How Content Affects Email Deliverability
15. Send Relevant Content That Your Subscribers Want To Read
Will your subscribers actually benefit from your email campaign?
Think before you send!
It doesn’t get simpler than that.
Ask yourself – do my subscribers expect this type of content?
Do your subscribers expect offers about laptops but you send them the latest movie blockbuster?
Then, chances are that they will end up unsubscribing. Or, even worse, reporting you.
Personalization and preference centers help with this. But it all comes down to sending content that is familiar to your subscribers.
16. Looks Matter: Be Consistent With Your Design
We don’t need to tell you how important branding is to marketing.
Your website and other marketing materials will have a consistent look. Your email campaigns should be the same.
It’s important to maintain a brand consistency throughout your newsletters.
Your subscribers are familiar with your brand identity. They won’t expect massive design changes between campaigns.
17. Mobile-friendly designs are no longer optional
Did you know that over 50% of email opens now occur on mobile devices?
Which means there’s no excuse for sending campaigns that look great on a desktop or web client, but suck on mobile.
In fact, there is a correlation between the complaint rate (or spam-iness) of your campaign and the absence of mobile compatibility.
A campaign that looks out of place on mobile devices will disengage subscribers.
And in some cases, it can lead them to unsubscribe since they cannot use their preferred mobile email client to read your brand’s newsletters.
So make sure your campaigns are mobile friendly.
18. Be Careful With URL Shorteners
URL shorteners are those handy little tools that take a long url and convert it into a short version.
For example, they may take:
and convert it to:
They are useful for cutting down the length of your URLs, but they are also good at masking where a link goes.
For instance, the shortened link above gives no indication of its final destination.
Which is why link shorteners are commonly used by spammers. They want to hide their malicious websites and blocked domains from users and mailbox providers.
Major link shorteners are public services and therefore nothing stops spammers from using them to mask their URLs.
We strongly advise against using these services as part of your email marketing routine.
Link shorteners have benefits, but they are outweighed by the shortcomings related to email deliverability.
If you must use link shortening as part of your email campaigns, we recommend implementing your own. Alternatively you can setup a tool like YOURLS and Phurl.
URL shorteners are a great way to improve the look of your email marketing campaigns. At the same time, URL shorteners entail the risk of unknowingly visiting an unreliable website.
19. Don’t Send Spammy Subject Lines Or Content
Your subject line is the only thing your subscribers read before opening your email campaign.
It has also been proven than mailbox providers, such as Gmail, “read” your subject and content and decide whether it contains spammy keywords or not.
We’ll be honest here.
No one knows the exact implementation of Gmail or Outlook’s algorithm for classifying messages as spam.
But a good start would be to avoid any spammy terms such as those listed here.
CAPITALS and misleading prefixes (such as RE: or FW:) also trigger spam filters.
Why start your subject with “RE:”, anyways, when you can get so much more creative?
2018 Bonus: Get free access to Refine, our brand new online tool, which predicts the open rate of your subject lines over the industry average!
20. Don’t Use Free, Personal Email Addresses For Your Campaigns
Your campaigns must fully represent your brand.
So there’s no point sending emails from your personal Gmail address.
The reason is simple:
A Gmail address is a personal email address. Which means your email campaign will most likely be considered spam by the various filters used by email service providers.
Ergo: it will not be delivered.
So use a professional email address, from a domain name recognized by your recipients.
From a technical standpoint, Gmail and other ISPs implement an extra layer of authentication called DMARC.
The popular email provider changed its policy a few years back and decided to penalize emails sent from Gmail addresses outside of Gmail.
DMARC stands for Domain-based Message Authentication, Reporting & Conformance.
The reason email providers adopt it is that it provides a further safety measure.
In fact, there are still instances where SPF and DKIM checks are not enough to ensure the recipient’s safety. DMARC adds an extra level of cryptography.
21. Always Include A Plain Text Version Of Your Campaigns, Along With The HTML Version
When sending your HTML email campaign, it’s good practice to also add a plain-text version.
Email clients are smart. They wlil display the most compatible version of your email campaign based on your subscribers’ settings.
This is good practice for email deliverability purposes.
22. Pay Attention To Image/Text Ratio (But Don’t Sweat It Too Much)
We’ll be honest.
Nowadays, image-to-text ratio plays a less important role in the spam filters of major inbox providers.
But to maximise email deliverability, it’s still something you should be aware of.
Spam Assassin recommends a minimum of 60% text and a maximum of 40% images in your email campaigns.
Our tests, and those in the industry, conclude that there is less of an issue with image / text ratio when other factors are satisfactory.
Part 5: Other Factors Affecting Email Deliverability
23. Use Double (Rather Than Single) Opt In For Your Lists
Opt-in is the explicit permission of a customer, or intended recipient of an email, to allow a marketing team to send messages with promotional information about their brand.
There are 2 common forms; single opt-in and double opt-in.
Let’s take a look at them.
What Is Single Opt-in?
An email address is added by any means to a mailing list.
However, no process is followed in order to ensure that the address belongs to whomever submitted it, or that any form of formal permission was given by the owner.
In other words the email owner has not confirmed their consent to be added to the list.
What Is Double Opt-in?
An email address is added by any means to a mailing list.
A confirmation email is sent to verify that the person the email belongs to consents to receiving messages. This is generally done by clicking a confirmation link. On occasion, consent can also be given externally, even offline.
So, a double opt-in registration is when confirmed consent of an email’s owner to receive messages is requested.
Double opt-in helps protect your mailing list from spam bots and other invalid signups.
You can expect the size of your mailing list to be slightly smaller than a single opt-in mailing list. But on the plus side, double opt-in is guaranteed to result in better email deliverability and inbox placement. Which is what we’re after, right?
Engagement rates skyrocket for double opt-in mailing lists. This helps your sender reputation and your email deliverability as a whole.
This higher probability of subscriber engagement makes inbox providers (such as Gmail) place your email in your subscribers’ inbox.
24. Segment Campaigns To Give Your Subscribers EXACTLY What They Want
A big factor in email deliverability is sending relevant content that your subscribers want to read. Unfortunately this is not always possible for big brands with large mailing lists.
The solution is to use segmentation to create subsets of your mailing list with common interests.
For example, you could send different campaigns to those interested in electronics vs those interested in buying sporting gear.
The good news is that personalization techniques have really improved over the past few years.
Automated sendings such as cart abandonment notifications and algorithmic product recommendations are achievable for every marketer.
Moosend offers a wide range of segmentation and automation capabilities. We highly recommended that you make use of them and send the right message at the right time.
25. Make It Easy To Unsubscribe (Seriously)
This might sound a little counterintuitive.
But you want to make it super easy for your list members to unsubscribe.
Hiding your unsubscribe links using various font sizes and color techniques only makes your subscribers lose patience and trust.
Worse still, they could mark your email as spam instead of unsubscribing.
The industry standard for complaints is 0.1%. This means that sending a campaign to 10,000 subscribers gives you only 10 tickets to the “Mark as spam” button.
Any more than that and your campaign is over the threshold. Which will put your sender reputation in jeopardy.
A footer offering a no-tricks unsubscribe link is a great way to keep your complaint rate low and maintain a high inbox placement.
Moosend, adheres closely to popular anti-spam regulation. We automatically add an unsubscribe link to every email sent using our platform.
We cannot overstate the importance of making your unsubscribe links obvious and clear.
26. Don’t Use A “No-Reply” Sender Address
“Do not reply” email addresses look like “firstname.lastname@example.org” and serve as a black hole for incoming mail.
Marketers often send their campaigns from such do-not-reply email senders.
These email addresses give the wrong idea to your users. Why should they not reply? Don’t you want to hear from them?
There is more than one reason to avoid no reply addresses. But above all it makes you look unprofessional and unapproachable.
It also massively affects your email deliverability and open rates. Check this post for more details.
Here’s a quick recap of the points we covered in this guide.
How To Maximize Email Deliverability In 2018
- Be Consistent With Your Volume
- Keep Your Lists Clean To Crush Bounce Rate
- Spam Complaints = Death For Your List
- Steer Clear Of Spam Traps
- Whatever You Do, Don’t Get Blacklisted!
- Use SPF To Verify Your Sender IP
- Use DKIM To Verify Ownership Of An Email Message
- Encrypt Your Email (Using TLS) To Build Trust With Users And Mailbox Providers
- High Volume Sender? Opt For A Dedicated IP Address
- Time Sensitive Campaigns? You Need A Dedicated Email Address
- Shared IPs For Everyone Else
- Monitor Mailbox Provider Feedback Loops
- Setup (And Monitor) An Abuse Reporting Mailbox
- Setup MX Records For Your Sender Domain
- Send Relevant Content That Your Subscribers Want To Read
- Looks Matter: Be Consistent With Your Design
- Mobile Friendly Designs Are No Longer Optional
- Be Careful With URL Shorteners
- Don’t Send Spammy Subject Lines Or Content
- Don’t Use Free, Personal Email Addresses For Your Campaigns
- Always Include A Plain Text Version Of Your Campaigns, Along With The HTML Version
- Pay Attention To Image/Text Ratio (But Don’t Sweat It Too Much)
- Use Double (Rather Than Single) Opt In For Your Lists
- Segment Campaigns To Give Your Subscribers EXACTLY What They Want
- Make It Easy To Unsubscribe (Seriously)
- Don’t Use A “No-Reply” Sender Address
Over To You
Follow the steps in this guide to maximise the deliverability of your emails. Your engagement stats will skyrocket.
If you have any questions or comments, then please leave them below.