How to improve the deliverability of my emails (advanced tips)

In this article, we share a few advanced tips to improve the deliverability of your emails and a few rules you should follow to ensure your deliverability remains optimal. 

These tips are for those who are familiar with the concept of deliverability. If you're looking for basic deliverability tips, click here.

One of our challenges is to ensure that we offer the best possible email deliverability for our users, and this involves stringent monitoring of outgoing emails from our platform.

The preservation of a good reputation of our domain and our IP addresses are fundamental to providing an efficient autoresponder. To ensure this, in addition to having a team dedicated to monitoring our infrastructure 7 days a week, we have put a series of essential rules in place.

It is essential to take note of this crucial point: the deliverability of your emails depends above all on your practices.

It is imperative that you measure your email deliverability statistics. 

From a practical point of view, we advise you to do 5 things:

1. Use a personalized and authenticated domain name,

2. Regularly clean your contact list of contacts in bounced status, unsubscribers, and especially those who no longer open your emails.

3. Send emails only to people who have agreed to it.

4. Understand the indicators on your emails.

5.  Analyze your statistics.

1. Use a personalized and authenticated domain name

Many receiving servers filter emails based on the incoming stream by setting up spam filters. In order to bypass this rule, the first step is to use an email address with a personalized domain name and authenticate it with our services.

As a result, you will gain credibility with your contacts, and from a technical point of view, the servers receiving the emails will take into account the reputation of your domain.

To authenticate your domain name, we invite you to follow the procedure described in this article and then contact Support for verification.

2. Clean up your contact list regularly

It is important to have a healthy contact base. For this, it is essential to keep a close eye on it.

It is possible to import contact lists into by following the procedure below

Nevertheless, it should be noted that the explicit agreement of all these contacts is a condition before importing them into

Imported contacts need to know that they are on your mailing list and what content you are going to send them. The aim is to minimize the possibility of your emails being flagged as unwanted. 

Therefore, we do not allow email addresses purchased or found on the internet (yellow pages, public profiles on social networks, etc.). reserves the right to suspend the email function as well as block the accounts of its users for any behavior likely to harm the efficiency of the service.

It is also very important to clean your contact list of all inactive or false email addresses, before importing them into your account.

Sending emails to non-existent recipients will lower your deliverability rate, and it can also damage the reputation of your domain name.

Your contact database may contain inactive/unsubscribed email addresses, which could directly affect your deliverability.

Email providers analyze your campaign data and penalize you when your emails are not opened. So it's very important to delete all your inactive or unsubscribed contacts.

Finally, once you have imported your contact list and started sending emails, make sure you clean it up regularly.

We advise you to clean it at least once a month, to keep only the responsive contacts, who open your emails. 

2.1 Remove non-existent addresses

There are 2 types of non-existent addresses:

  • Old email addresses of customers that may have been closed or deleted
  • Misspelled email addresses, which are currently automatically deleted by our system.

On, and thanks to the filters available on your contact list, you can obtain the list of your contacts in "Bounced" status with one click.

We invite you to follow the procedure described in this article.

2.2 Delete inactive addresses

Your inactive contacts cause your open rate to drop, which directly impacts your reputation with email providers.

Some addresses become inactive for several reasons:

  • Your emails go to spam and are no longer seen by the customer
  • The customer is no longer interested in the activity/services you offer
  • Your customer receives too many emails and does not open all of them

To manage these inactive addresses, you will first need to classify them in a new list by adding TAGs.

You have 2 options:

  • Undertake specific re-engagement campaign: If you want to opt for re-engagement on specific campaigns, we recommend that you only do so if your list is segmented, otherwise, it's not a recommended practice.
  • Permanently remove these addresses: If you decide to get rid of these contacts from your list, you can use the filters provided in to delete the contacts according to the timeframe you have chosen for this purpose. We invite you to follow the procedure described in this article.

2.3 Implement double opt-in

What is double opt-in?

When your contacts register on a double opt-in registration page, they will receive an email containing a link to confirm their registration.

If the contact has not clicked on the confirmation link within 24 hours of signing up, they are automatically removed from your contact list.

There are several advantages to implementing double opt-in:

- This encourages the registration of contacts with valid email addresses and prevents bots from remaining on your contact list as they will not be able to validate their registration.

- This also allows for double confirmation of acceptance of receipt of your emails. 

This option is available on How to set up double opt-in

3. Follow good emailing practices

Sending emails to your contacts is a great way to keep in touch and not be forgotten, but you have to do it properly.

3.1 Send targeted emails

In an email marketing campaign, knowing your target audience is essential. This allows you to address only those people who are interested in your content or offer. 

Good targeting means ensuring that the contacts on your list are interested in what you have to offer, and therefore more likely to open and read your emails.

If you send your campaigns to all your contacts without any personalization, you risk having poor open rates. Always keep in mind that not all your contacts are interested in the same things. If you constantly offer them content that doesn't match their interests, they may stop opening your emails, unsubscribe, or spam you.

To keep their interest, you need to segment your contacts according to their preferences to better share your content by targeting their expectations. To do this, you can use TAGs.

Finally, never send emails to contacts who have not given you permission. This will ruin your statistics.

Furthermore, buying a list of contacts is strictly prohibited

3.2 Take care of your objects

The subject line of an email is the first window of your message, but also of your business.

It is the first opinion that your prospect will have of your message. It is also with the title that your contacts will decide whether to open your emails. Optimizing it therefore directly influences the opening rate of your emails.

There are several good practices to follow: 

  • Don't leave the subject empty
  • Avoid shocking, controversial words and capital letters
  • Limit special characters, such as exclamation marks and question marks

The subject line should convey that you are trying to provide value to the recipient. To spark the recipient's curiosity, inserting personalization elements in the email subject line can help increase the open rate. 

Please note that due to the restrictions that have been put in place on certain servers, the control filters have become stricter concerning consistency between the name of the sender of the email, its title, and its content.

We are obliged to invite you to be more vigilant as to the coherence between these three elements. 

If you offer pre-written sequences to your affiliates/customers, it is essential to inform them of the need to edit the emails with consistency between these three elements.

If, in other circumstances, you use pre-written emails as part of product promotion, it is also important to respect them.

Also, and in essential respect of the ground rules, it is forbidden to use the identity of a third person or company.

It is preferable to use only one sender name per account/email address, so "your bank", "the accounting department", etc. are prohibited and may be blocked by the team.

Example of a bad email:

Title You have just received a transfer of $200 to your bank account    
Sender Your bank    
Content Hello, Would you like to receive this type of notification on your account? If you are interested, please join our program at the following link soon. Our offer expires in 2 hours.

The title, however attractive, does not reflect the content of the email. People who do not understand the nuance may mistakenly believe that the email is from their bank or that it is a scam.

The sender's name is also inappropriate, as you are not a bank.

Finally, following the restrictions issued by "Gmail", we ask you not to use link reducers on your emails (Bitly, TinyURL...) 

We also advise you to use links to your downloadable files instead of attachments.

These measures have been taken to improve the deliverability of emails for all users and to preserve the reputation of our IP addresses.

If, however, this is not respected, and in the interests of security, we will be obliged to suspend the sending of emails from accounts that do not respect these essential rules.

3.3 Beware of "spam words"

Spam detection by artificial intelligence has evolved significantly. Today, tools are not only based on the presence of a word but also on:

  • The context of the email
  • The number of occurrences of the word
  • Its placement in the email
  • Its spelling

To determine in which folder (Main Box, Promotions, Spam...) an email will be filed, email providers scan its entire content.

"Spam words" are words to be avoided as they can contribute to your message being put in the spam/junk folder. It is therefore essential to pay the necessary attention to them.

3.4 Make it easy to unsubscribe

When a user receives an email they do not want, they will be faced with 3 options:

  • Unsubscribe
  • Stop opening emails
  • Report the email as spam

Being regularly reported as spam will have a catastrophic effect on your deliverability and may even get you blacklisted from email providers. If the customer simply stops opening your emails, you will also lose deliverability and your click-through rate will drop.

Therefore, unsubscribing is by far the best option.

There is no magic wand to improve your deliverability rate. You simply have to be rigorous, respect the basic rules, and keep in mind that your statistics will always depend on your practices. 

3.5 Sign your emails

It is also important that you can be identified on your emails (note that this is necessary if you send emails to German servers for example).

Indeed, it is important to add in the footer of your email:

- Your name, brand name, and information

- If you are a company, its name and the link to your website.

Finally, it is also strongly recommended that all links in the email, as well as the sending domain name, point to the same (accessible) domain.

4. Understand the indicators on your emails

With, users are divided into pools and each pool uses different sets of IP addresses.

The reputation of these IP addresses is one of the most important factors in ensuring email deliverability, which is why it is necessary to maintain good statistics to be in the best pools.

We assign users to pools based on the performance of certain metrics and in particular to maintain the reputation of these IP addresses.

Green pool: excellent statistics

Yellow pool: average statistics

Red pool: poor statistics

Quarantine pool: for new users with bad statistics

Gray pool: new users - they will be moved to one of the four pools as soon as they have sent at least 500 emails

4.1. The rules:

  • Users are allocated to different groups every morning
  • A user must use as a client for at least 16 days to be placed in a pool other than the new user pool
  • A user can only be moved from one pool to another after having been in the current pool for at least 14 days
  • A user can only be moved from one pool to another after having sent a certain number of emails in the current pool:

NEW USER (Gray) → 500,


LOW RISK (Green) → 5000,

MODERATE RISK (Yellow) → 5000,

HIGH RISK (Red) → 5000,

Note: we check emails sent from the date of the last pool change up to 5 days before. We need these 5 days to collect email deliverability statistics, such as:

  • Bounced rate
  • Spam reports
  • Open rate
  • etc.

There are 3 main statistics to monitor:

  • Bounced rate: this is the percentage of emails rejected by the receiving servers, compared to the number of sent emails

    These rejections can be due to different reasons (false email addresses, deactivated email addresses, blacklisted domain names, incidents on the receiving servers, etc.).

  • Spam reports: this is the number of your contacts who manually report your email as spam, as well as the percentage in comparison to the number of opened emails
  • Number of opened emails: this is the number of openings of the email in question as well as the percentage in relation to the number of emails sent

4.2 Thresholds:

The following are the thresholds for moving a user from one pool to another.

High risk:


0.4% < SPAM REPORT < 1% (min 6 spam reports)

1.8% < Bounce Rate > 5% (min 30 bounced emails)

Moderate risk:

10% < OPEN RATE < 20

0.25% < SPAM REPORT < 0.4% (min 6 spam reports)

0.7% < BOUNCED RATE (bounce) < 1.8% (min 30 bounced emails)

Low risk:

OPEN RATE > 20% 


BOUNCED RATE (bounce) < 0.7% 


Emails sent in the last 24 hours are checked.

If any of the thresholds are exceeded, the user is immediately moved to the quarantine pool:


BOUNCED RATE (bounce) > 5%

We check at least 1000 emails sent up to 5 days before.

If you are in the quarantine or red group, we advise you to follow the indications above as well as the following help page to properly interpret your statistics and correct them to improve the deliverability of your emails.

5. Analyze your email statistics

To ensure good email deliverability, we monitor our users' activities daily.

If we notice that any of the indicators are abnormally high, we suspend the sending of emails from the user's account as a security measure (this is done in the interest of all users).

Here are some indications to interpret these figures:

  • Bounced rate:

Less than 0.5% => OK

Between 0.6% and 1.9% => Try to find the reason.

2% and more => Critical problem, contact our customer support as soon as possible.

  • Spam reports:

Below 0.08% => OK

Between 0.08% and 0.19% => Find the reason why you have so many spam reports.

0.2% and above => Critical problem, you need to contact our customer support as soon as possible.

  • Open rate:

20% and more => Good open rate.

Between 10% and 20% => Average open rate.

Less than 10% => You need to clean your contact list.

Annex Articles:

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