How to improve your email deliverability

Here is some advice on how to improve your email deliverability.

But before we get started, you must understand something fundamental:

Email deliverability depends mostly on your practices

We do everything to guarantee our users the best possible email deliverability,
but in the end, email deliverability largely depends on your practices.

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

The reputation of these IP addresses is the single most important factor when it comes
to email deliverability.

We categorize users into pools depending on their email statistics to ensure that the reputation
of these IP addresses is maintained.

Green pool: excellent statistics

Yellow pool: average statistics

Red pool: poor statistics

Gray pool: new user - you will be moved to one of the three pools (green, yellow, or red) as soon as you have sent 500 emails

The rules:

  • Users are moved between pools every day in the morning.
  • A user must use SI as a customer for at least 16 days to be moved from the beginner pool
  • A user can be moved from one pool to another only after being in the current pool for at least 14 days.
  • A user can be moved from one pool to another only after sending a certain amount of emails in the current pool:

NEW USER => 500,
LOW RISK => 5000,
HIGH RISK => 5000,

 we check emails that were sent from the date of the last pool changing up to 5 days ago. We need these 5 days to collect email delivery stats: Spam reports, open rate, etc.


To High risk:
0.4% < SPAM REPORT < 1% (min 6 spam reports)
1.8% < BOUNCED > 5% (min 30 bounced)

10% < OPEN RATE < 20%
0.25% < SPAM REPORT < 0.4% (min 6 spam reports)
0.7% < BOUNCED < 1.8% (min 30 bounced)

To LOW risk:
0.7% > BOUNCED

Emails that were sent during the last 24 hours are checked:
If one of the thresholds is exceeded then we move the user to the quarantine pool:
We check at least 1000 sent emails that we sent up to 5 days ago.

If you are in the red or yellow pool we advise you to read this article very carefully to increase email deliverability:

Tips to increase your email deliverability:

To ensure good email deliverability you must pay attention to the following points:

Only send emails to people who have given you permission

This is the basis for ensuring good email deliverability

If you send emails to people who have not given you permission (for example by purchasing an email list) many people will mark your emails as spam and many emails will "bounce" (that means the email could not be delivered, usually because the email address does not exist).

This will strongly affect your email deliverability

For these reasons, with you can send emails only to people who have given you permission to do so.

We control the activity of our users and if we notice that your email rates have very high spam or bounced reports we will shut down your account (this is in the interest of all users of

Monitor your email stats

In your dashboard, you can see the statistics of your emails.

Here are some guidelines to interpret those figures:

Bounced emails:

Below 0.5% => OK
Between 0.6% and 1.9% => We must try to find why
2% and more => Critical problem, we must contact our support as soon as possible

Emails marked as spams (it means that the contract has marked your email in spam in its email box):

Below 0.08% => OK
Between 0.08% and 0.19% => you must find the reason why you have so many spam reports
0.2% and more => it is a critical issue, please contact our customer support as soon as possible

Delete inactive contacts on a regular basis

Having a huge email list feels good but if too many contacts stop opening or clicking in your emails it can affect your email deliverability.

We recommend that you delete the inactive contacts regularly.

For example, every 3 months you can search all the contacts that have not interacted with your emails for 3 months and delete them

(there is a filter that allows to find them on the contacts page in

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