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How to Guarantee more emails are Delivered to the Inbox

The single most important part of any email marketing campaign is to make sure your emails reach your intended audience.

We know a lot of marketers and major companies struggle with this so I have put this guide together to provide key points that require action which will help enormously with getting more emails delivered to the inbox by having a better sender reputation

If you are a bigger client and send a range of different emails like transactional, newsletters, updates, receipts etc and you use a dedicated server, set up separate IPs for each type of email you send

Set up your main domain name to send company transactional emails and set up variations to send other types of email, so set up your company domain name/news etc from separate IPs and this way Google and other IPs wont group all of your emails in the promotions tab

Use double opt-in

The old favourite but it is important and requires each new subscriber to confirm the email you send them to confirm they want to receive your emails

Whilst this will result in lower overall subscribers being added to your list compared to single opt-in, the overall quality and open rates will be far superior and removes the possibility of bots signing up which will cause you possible spam issues


If you are an InboxingPro customer you know we create all of records to add to the DNS editor to validate your domains

If you are not an existing customer the following validation is critical to help with your sender reputation

Use SPF authentication

Also known as "Sender Policy Framework", this is an authentication protocol that states whether an IP is authorized or not to send emails for a domain.

Here are a few places with useful resources about SPF:

Unlock the Inbox - SPF Guide


Here are some SPF Testing tools:

Unlock the Inbox - Mail Tester

Scott Kitterman's SPF Validator

Use DKIM Authentication

Also known as "DomainKeys Identified Mail", this is a protocol that allows other mail servers to verify whether the email you sent has been tampered with or not. Basically, it verifies whether the email received from a specific domain was indeed authorized by the owner of that domain.

Here are a few places with useful resources about DKIM:

Unlock the Inbox - DKIM Guide

The DKIM Project

Here's an easy wizard to help you create your DKIM Record

Unlock the Inbox - DKIM Wizard

Use DMARC authentication

This is a very important record and provides both the SPF and DKIL records and this is used by all the big ISPs

Shortcut for "Domain-based Message Authentication, Reporting & Conformance", this is an authentication method that prevents phishing attacks and reduces spam. It enforces a policy that tells the ISP what to do when it receives emails, apparently from your company, that fail either SPF or DKIM.

Here are a few places with useful resources about DMARC

Unlock the Inbox - DMARC Guide

The DMARC Project

We create the SPF and DKIM records automatically in our autoresponder  app and provide video tutorials to add the records to the DNS editor

Use a reputable DNS Provider

Mail delivery depends a lot on being able to retrieve records from DNS.

ISP's also check the reputation of your nameservers. Here are a few DNS Providers:

DYN Managed DNS - Provides a lot of tools and options to secure your DNS Properly.

Cloudflare - Provides DNS Management and a suite of optimization tools.

DNS from large registrars should be fine, although we have seen slowness in some registrars applying DNS changes.

Use a reputable CDN for static content

Also known as "Content Delivery Network", it caches versions of your content around the world.

There are four main reasons to use a CDN:

To provide faster load times for images included in the emails you send.

ISP Providers won't block them since they are known and reputable.

You will also benefit from DDOS protection which keeps your website online even if it`s attacked.

You will benefit by default from an advanced firewall that can help mitigate some of the classic attacks looking to exploit your website.

CDN Providers:


Microsoft Azure CDN

Amazon CloudFront

DNS Example

A Record ( > "Points To" > PTR Record > "Points to" > Hostname ( (Forward)

Hostname ( > "Points To" > PTR Record > "Points to" > A Record ( (Reverse)

ISP Providers won't block content from CDNs since they are known and reputable.

Use PTR records (Reverse DNS Lookups) for your sending IPs

This is mandatory. Most ISPs require FCrDNS (Forward Confirmed Reverse DNS). It sounds complicated, but it's really not.

Here are a few resources on FCrDNS:

Unlock the Inbox - PTR Records.

SPFBL - Introduction to FCrDNS

Here are a few places to test FCrDNS at:

Unlock the Inbox - Mail Tester

Junk Email Filter FCrDNS Test

Warming up your IPs

If you have set up a new IP and domain name it is important to slowly introduce this to the ISPs

Warming up IPs is important

Don’t send too many emails at once. If your sending platform supports it and does, use limits per hour or per day for each of the IPs per domain. If you send too many mails at the beginning, you can get bounces and/or deferrals.

Here are some limits, per provider, that you should follow in the first 30 days

Yahoo: 200 emails/day/IP (for at least 5 days), then you can double every day.

Gmail: 200 emails/day/IP (for at least 5 days), then you can double every day.

Hotmail: 200 emails/day/IP (for at least 5 days), then you can double every day.

AOL: 200 emails/day/IP (for at least 5 days), then you can double every day.

Cloudmark (all domains): 50 emails/day/IP

Time Warner: 100 emails/hour/IP

Cox: 100 emails per connection per IP, up to 5 IPs

You should always visit the postmaster website of the domains you are trying to send to in bulk. A lot of times you'll find the sending limits published within their bulk sender guidelines.

We have published a post here to set up 4 of the main ISPs postmaster tools

Warming up your IP can also be beneficial if you find your delivery declining or you may have changed hosting etc

Several other examples on how to warm up your IPs:

Start a new warm up for the existing IP.

Send only to subscribers who have opened at least one of your emails in the past 30 days.

Limit your starting volume to 3,000 subscribers.

Keep sending to those subscribers only, for the first 3 days, before increasing the volume.

Increase the volume by 1,500 subscribers with opens in the last 30 days. Your new total volume should be 4,500 subscribers.

Keep sending to the new volume of 4,500 for two more days.

Follow this strategy to increase the volume every two or three days by 50% of the actual volume.

After 10 days, you can start increasing the volume by doubling it.

Feedback Loops (FBL)

Register to all FBLs

Also known as complaint feedback loop, it is a service offered by some ISPs that report back complaints (when a subscriber hits the spam or junk button in their inbox) to the sender. It's provided to aid senders in keeping a clean list and preventing the subscriber from getting unwanted mail.

Feedback loops are provided by some ISPs to aid senders in keeping a clean list and preventing the subscriber from getting unwanted mail

Gmail has a feedback loop that is only available for ESPs who are MAAWG members and are approved by Google as good senders.

To be sure that your email doesn’t end up in a recipient’s spam folder, maintain your sending reputation:

Keep an eye on your email deliverability.

Look at subscriber engagement and try to keep your complaints rate within 0.2%.

Monitor delivery errors.

Clear your mailing list from bad and invalid addresses regularly.

Your sending reputation is always in your control, so take advantage of postmaster features, analyse the data, and watch your score grow.

Email Blacklists

Make sure your domain/IPs are not on any blacklists before you send

Many companies use the same blacklist providers, so being listed on a single blacklist can affect your delivery to many different ISPs.

There are a few different types of blacklists

Public - These blacklists are published so any ISP can use them. They are the easiest ones to monitor using automated tools.

Private - These are paid blacklists - The only way to actively monitor these is to use inbox testing tools to check your delivery.

Internal - These are maintained by the ISPs directly. They can be monitored with inbox testing tools, as well.

Some ISPs use multiple blacklists, so it's very important to monitor all aspects of your sending using the different tools available.

Here are our favourite tools for checking if your domain/IP is on a public blacklist: - The fastest and easiest to use


Whitelisting Services

Whitelist your IPs after 90 days of sending

The reason you have to wait 90 days, is that some whitelisting services require to see your sending history.

Whitelisting your IPs provides many different benefits at different ISPs:

Increased inbox rates

Increased Sending Volumes

Less restrictive spam filtering

Free whitelisting services




DNS WL - Helps with places that use Spam Assassin.

Paid whitelisting services

Return-Path - This is one of the best whitelist programs.

CSA (Certified Senders Alliance) - Based out of the EU.

Email List Quality / Sender Score

Try to avoid buying and renting an email list, even if it’s from a reputable provider. ESPs have ways of detecting if a list is bought or rented and they can/will reject it when you will try to import it into their mailing platforms. No email validation company can help you here and the reason has nothing to do with the validity of the email recipients.

Try to get an open rate of at least 15% and a click-through of at least 1%.

We also recommend removing all non-opener emails after 6 months. These emails are probably valid, but not in use.

A lot of domains use Sender Score as a determining factor to allow emails from your IPs. If your Sender Score is less than 90 you should take action to improve it.

Monitor Your Sender Score

Domains use Sender Score to determine whether or not to allow emails from certain IPs. If your Sender Score is < 90 you should take action to improve it. You can monitor you Sender Score: Here

General good housekeeping tips


Use the recipient's name in the subject line and in the header of the html (e.g.: "Dear John"). Make sure you check for spam words and domains in the HTML. (for example, if you use a domain in any of the links in the html that is present in a DBL (Domain Blacklist), your email might bounce). Inbox Test every campaign you're going to send and make adjustments where needed.

Remove inactive emails

We recommend removing non-opening emails or non-clicking emails after 180 days. A lot of ISP algorithms are based on user engagement. The more non-openers and non-clickers, the worse the statistic gets and the worse your inbox rate becomes. After six months, you can also retry sending to these email addresses to see if the recipients open or click.

Use a Reply-To header that is valid

We all receive emails from noreply@, but it's actually better to have a functional Reply-To that's monitored and customers enquiries are responded to. The more engagement between you and your customers, the better your deliverability.

Send 1 email per connection

You should only send emails to 1 person. You've seen those emails where you have a large number of "CC" or "TO" recipients. This is a huge spam flag. When sending out bulk emails, ensure each email is addressed to a single person and not multiple contacts at once.

Enable outgoing TLS connections

Mail servers are supposed to be opportunistic in nature and what that means is they all prefer to use the most secure protocol when accepting mail - TLS 1.2, TLS 1.1, TLS 1.0, NO TLS in that order. Some mail servers will refuse all non-TLS transmissions, so in order to achieve maximum deliverability, you should always enable TLS when sending email.

Ensure that your abuse/complaint rates remain low

Once you sign up to the FBLs (Feedback Loops), as discussed earlier in this document, you need to actively remove those subscribers from your mailing list when you receive the alerts, in order to keep your abuse/complaint rate low. When these metrics get too high, they will affect your deliverability.

Do not use private WHOIS for your domains

All registered domains are required to have accurate information by ICANN. Hiding behind private WHOIS can hurt your domain reputation and, in some cases, it is even illegal (CAN-SPAM Act).

Have a functional and complete privacy policy on your website

When asking for ISPs to whitelist your IPs/Domain, they do look for your privacy statement and verify it.

Remain consistent in your sending behaviour

Send your newsletters, promotional, marketing materials on the same day, every week/month. Being consistent proves you have a real business and keeps your IPs warm.

Do not segment emails per destination ISP

Separating your e-mails based on destination, unless under special circumstances, has a detrimental effect. Some domains will use SenderScore for reputation lookups, but those IPs will never get their sender score increased because they don't report back to Return-Path.

Do not send affiliate email marketing

Most ISPs blacklist the subject lines and content for this type of email. Remember, everyone is sending the same affiliate promotion. ISPs have AI that learn subject links and content, and your IPs will get blacklisted or are going to be limited to only being able to send to the spam folder. Normally, ISPs will accept and won’t complain if you add an advertisement to your normal newsletter.

Laws and Compliance

Honour all unsubscribe requests

Whether it's through an automatic unsubscribe link or manually requested, honour it. The sooner you honour it, the better. Never wait more than 10 days to do so, this is a requirement of the CAN-SPAM law.

Set up an email box monitor

You can define conditions so that while InboxingPro processes the emails found in the account, it will take certain actions if it finds certain content. For example, you can tell it to unsubscribe subscribers from the email list in case it finds the phrase “unsubscribe me”.

This feature is really useful when people reply to your email campaigns and tell you to unsubscribe them for example. This way you will spare valuable time since the process can be automated.

Comply with the law: CASL for CA, CAN-SPAM for US, DPEC for EU and other local anti-spam laws

When you're in compliance with the law, everything becomes much easier to whitelist

When you're in compliance with the law, everything becomes much easier to whitelist and managing your reputation will be free of obstacles.

Here are the links to some of the major e-mail laws:

Can-Spam Act (US)



MX Records

Your domain has to have valid MX records

Although the RFC states that if the MX record is missing, one should use the A record as the mail server. We noticed that many ISPs don't follow the standard and they check the validity of your MX Record before allowing email from your domain. If you're looking for a good mail service provider (ISP) for your domain, we recommend using G-Suite from Google.

Hosting options for email marketers

Choosing a hosting package can be quite a complicated task and the 1 thing you should never base this decision on is price alone

In this post I will explain the basic options available and give the pros and cons for each and then I will provide details of our brand-new hosting package which has been designed by us specifically for our InboxingPro autoresponder customers

Basic shared hosting

This is what most marketers start out with because it is very cheap and does the job of hosting a few websites

Shared hosting allows you to rent space on a shared hosting server along with hundreds if not thousands of other customers, every server has a maximum capacity to store data and send emails, you can find a lot of offers that claim to offer unlimited everything for a few dollars per month, in reality you will get a few customers taking the majority of the space which means the service is slow and sluggish but the biggest issue for email marketers is you cannot add your own domain name to the DNS to help validate the records and in most cases the shared IP is always blacklisted so shared hosting is not recommended for anything but storing data and websites that don’t attract much traffic

VPS Hosting

VPS Virtual Private Server (VPS) Hosting is a cross between Shared & Dedicated. A physical server, called the parent, runs several VPS instances, which are granted a strict portion of the parent server’s hardware resources.

These instances are rented out and operate as independent servers from one another, so it’s essentially renting part of a dedicated server.

These plans range in prices and offer easy affordable scaling and better performance or security than a shared hosting website.

You also normally get a dedicated IP and for an additional fee you can also get a cPanel license to access the DNS editor to add the records to verify the sending domain has a good reputation

Dedicated Server Hosting

The dedicated server is the top tier of web hosting, Dedicated Servers are just what the name implies, a server dedicated to you.

All the hardware that makes up the server is under your control. Dedicated servers often share network access with neighbouring dedicated servers in a data centre, but they share no hardware and each one is dedicated to its own customer.

 These plans tend to be the most expensive but give you the best performance, security, and flexibility.

As you can see each of these hosting products work in different ways. This means each will have its own strengths and weaknesses over the others.

So, let us compare Shared Hosting vs VPS vs Dedicated by a few different metrics to see how we obtained this tier structure.


Performance matters. If you want to keep your customers happy, you need to provide them with top-notch performance. A survey conducted by Kissmetrics discovered that nearly half of web users expect a site to load in 2 seconds or less, and they tend to abandon a site that isn’t loaded within 3 seconds.

Furthermore, 79% of web shoppers who have trouble with website performance say they won’t return to the site to buy again and around 44% of them would tell a friend if they had a poor experience shopping online. The bottom line here?

It takes only a second of difference from slow page loads to lose out many potential or even perpetual sales.

Poor Performance – Tradational Shared Hosting

These plans generally include very limited resources as they are granted only a fraction of the available system hardware. They can find themselves robbed of resources by other sites on the same server monopolizing them. The Shared Hosting tier is good for low traffic and static websites.

Good Performance – VPS Hosting

VPS plans are limited by the available hardware assigned to the plan. There is a performance tax on the hardware when running in a visualized setup. However, this tax has become smaller and smaller over time allow more comparable performance levels to Dedicated Servers.

Great Performance – Dedicated Server Hosting

Direct access to the hardware provides the best possible performance configurations with a dedicated server.

InboxingPro hosting

You may know we have recently undergone a major server upgrade and migration and we now have super-fast servers with tons of memory

We have explored the option of providing exclusive hosting and now we have a lot of spare capacity from our new server structure we have designed a totally unique package designed to get the best possible email delivery and host fast loading websites

The biggest issue with hosting and email delivery is unless you can add records to the DNS editor to validate the sender domain you will never get any decent delivery

Our new service takes advantage of the low-cost shared hosting to store your websites and files etc but we have added a dedicated IP and cPanel access, so you get the benefits of sending emails as a trusted sender but without the cost of a dedicated server

Unlike a typical shared hosting set up, we are also using super-fast SSD disks and we are limiting the number of customers to 100 per server to ensure everyone can have their own exclusive storage space with fast website loading

Because we control and manage the servers, we can send thousands of emails per hour and we have included a choice of email sending limits and disc space to maximise cost savings

We think this brand-new service is perfectly positioned to provide everything an email marketer getting started needs to get outstanding delivery and enjoy massive savings compared to other email sending options 

You can get started hosting websites and sending 5000 - 10,000 emails per day (up to 300,000 per month) for less than just $16 per month which includes 5-10GB SSD disk space, a dedicated IP and full cPanel access

Please click here to get the details

You can use an existing domain name to host the service or you can buy a new domain directly in our new hosting platform

If you want help to use the new server with the InboxingPro app we provide an additional set up service costing $30 but for a limited time we are including this in the offer and we will have you up and running within 24 hours sending emails for free from your own dedicated IP

Should you use Emojis in your email subject lines

The subject line is the most important sentence of your email. A boring subject line will mean your email is overlooked or just deleted. 😲

Meaning all the hard work writing your email would have been for nothing!

It gets worse…

If your subscribers continually don’t open your email, you may begin to get marked as ‘spam’ by the email client (for example: Gmail, Outlook, Apple Mail). As email clients get more and more sophisticated about identifying which emails are engaging, and which emails shouldn’t even make it to the inbox.

So now you can know how important it is to get the subject line right, let’s see how we can make sure yours stand out.

Will Emojis Help Your Email Stand Out?

To avoid sending mundane subject lines to your subscribers, you’ve probably considered including emojis. But do they really grab readers attention?

Other email users seem to think so…

There has been a staggering increase in the use of emojis in subject lines.

Email marketer Jess Nelson reported that emoji usage has increased 775% year on year — (so you know, just a little bit). But could that mean you now blend into the crowd?

Turns out no.

While the increase has been massive, the percentage of people using emojis is still relatively small. According to Econsultancy, just 5% of subject lines in 2017 included emojis.

Will an emoji increase the chances of my email being read?

Other marketers are seeing success from using emojis when used well.

Many claim that emojis help your content stand out in an inbox dominated by text, and that when used strategically and sparingly, they do increase open rates.

Swiftpage, for example, did their own set of tests to determine the impact of emojis in subject lines. Here’s what they found:

  • 29% increase in their open rate (number of people who open the email)
  • 28% increase in the click through rate (number of people who click on a link in the email)

ReturnPath also tested emojis in their emails across multiple holidays and found some interesting results.

On Valentine’s Day, the use of lips in their subject lines increased their open rate by 4%.

On St Patrick’s Day the use of the Irish flag emoji increased open rates by over 6%.

 And they also found that the poop emoji was the most effective across other days of the year. Weird.

If you are a customer of InboxingPro, you will know we include a library of emojis in the campaign editor and you can simply select the emoji you want to add to the subject line and its added automatically

If you are not yet a customer, click here to see our current offers or click the link below to access a free selection

Click here to access a massive range of free emojis to use in your campaigns

It’s not all roses 🌹 for emojis

It can go the other way too. Econsultancy tested 14 different emails, each with multiple variations of the same subject line. They sent each email to over 10 groups of 50,000 people and recorded the results.

They found that 60% of the time an emoji increased the open rate (over the same subject line with no emoji). This means that 40% of the time, the emoji had a negative impact.

And popular isn’t necessarily better

There is data around the most popular emojis (see the list from Mailchimp below), but again, this doesn’t mean that they are the most effective. I suggest testing popular and different emojis to see which ones resonate with your audience the most.

Send half of your emails out with no emoji, and half with. See which gets the better open rate. Do this over the course of a few different email types to find a pattern and see if emojis really do work for you.

 Then try testing different types of emojis and use of multiple emojis to see which your subscribers prefer.

Emoji Subject Line Recommendations

If you are going to test using emojis in your email subject lines, there are a few tips I recommend.

  1. Use emojis sparingly: too many will make your email appear spam-like.
  2. Test your emails: your subscriber base is different, test to see which style they prefer.
  3. Render: make sure you are testing your email in multiple email clients, browsers and devices before sending to make sure the emoji appears correctly.
  4. Improve: take the learnings from previous emails and let them impact future subject lines.
  5. Write, write, write: create multiple variations of your subject line, with different emoji options and give yourself time to choose the best one, it is the most important piece of content of your email after-all.

Sorry — It’s Not That Easy.

Unfortunately, not all browsers and email clients display the same emojis in the same way or at all (check out this article on all the different ways the same emoji can look).

 So, while you might see your sunshine emoji just fine in your test email to a Gmail email address that you opened in Chrome, your recipients who open their email on another email client on their mobile might not see the same thing.

You will have to test multiple email clients and browsers to know for sure. Otherwise you could end up sending an email with this symbol in it ▢ or the word ‘emoji’.

Note: check how the subject line looks when you open the email too! Some email clients display subject line emojis differently within the email.

Could Emojis Impact Deliverability?

According to Experian, emojis shouldn’t impact upon your emails deliverability. So, if you’re seeing a lot of hard-bounces (failed sends) from your emails, then there are probably other factors at play.

To delve deeper into your low deliverability, start with your subscriber list:

  • Should these people be getting this email?
  • Are they all expecting and wanting to see your content?
  • Could you make your emails more relevant and engaging to them?
  • Are you sending emails at the right time for them?
  • Are your emails designed well and rendering correctly across all email clients that they use?

All of the above questions will help you determine why your deliverability is low.

Unfortunately it isn’t as simple as including or excluding an emoji.

So What’s The Final Verdict?

Should you include emojis in your email subject lines? Yes, you can and should trial using emojis!

But you need to work on writing a good subject line first. Then add relevant emojis sparingly to amplify their effectiveness.

Thanks to Amy Baker, Medium for this article

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