General recommendations

Double Opt-In. The recipients explicitly expressed their wish to receive the information before mailing

Make sure that you send emails to the users that have explicitly expressed agreement to receive them. For instance, they can manually mark the checkbox “Subscribe to our newsletters...” or “Agree to receive updates, alerts and promotions” in the registration or subscription form (we highly recommend having no default mark in the checkbox). We also advise to take GDPR rules into account if your subscribers can be EU citizens.
A user must confirm ownership of the indicated account. The following actions are considered as account confirmation:

  • sending a confirmation code in a reply email;
  • clicking a subscription confirmation link in an email;
  • entering an activation code in a corresponding field, the code must be taken from an email sent to the indicated account.

You should not carry out mailings using database of email addresses that was taken from third parties or collected from third-party sites.

OAuth-authentication. Subscribers logged in on your site using "with" button

When using OAuth-authentication you have no need to use double opt-in since a user confirms ownership of the indicated account entering its login and password (this data is not transferred to the site, the user does not take any risk).

Due to the same reason the number of invalid (non-existent and blocked) addresses will be reduced to zero during the registration.

How to avoid mailings problems using OAuth-authentication:

  • Do not hide agreement to receive mailings. Show the information about the mailings during the authorization instead of hiding it in user agreement or any other documents;
  • Unmark the checkbox. Remove the tick next to the agreement to receive mailings. Allow users to decide themselves whether they want to receive mailings;
  • Send a notification. After OAuth-authentication send a notification about registration and mailings with he possibility to unsubscribe within this email.

Here you can find detailed information about "with" button:, technical information: .


Use DomainKeys Identified Mail (DKIM) authentication technology. This tool can provide you with a consistent reputation within your domain, without reference to IP addresses, which are used for mailing.

Instructions on how to unsubscribe from the mailing

Unsubscribing via a link in a body of an email

Provide each email with a clear and noticeable instruction on how to unsubscribe from the mailing. Make the process of unsubscribing from your mailing as easy as possible.

Make sure that it is really easy to unsubscribe from your mailing, just by clicking a link in an email for example, without requiring any complicated actions from users, like entering and restoring password, registration and others.

Users should not sign into a website in order to unsubscribe. The process of unsubscribing or deleting email addresses from your database should happen without delay, immediately after user’s expression of such intention.

Unsubscribing via a button in an email

We advise you to include valid email header List-Unsubscribe to each email from mailings, which allows immediate unsubscribing. The process of unsubscribing should happen right after passing through the indicated URL or getting an email to the indicated email address.

It should be done without requiring of any additional actions from users, as this process is performed automatically and the result is not visible for a user.


List-Unsubscribe header content is processed in accordance with RFC 2369. It is not recommended to use free mail system addresses in <mailto: ...> construction. Monitor the efficiency of the selected unsubscribe variant.

Complaints about spam 

Many senders are blocked because of users’ complaints about Spam, as it is difficult for users to  unsubscribe or to remove themselves from the list of recipients of such mailings, and that is why they report Spam.

It is recommended to keep all data about when a user subscribed to a mailing (IP address; date and time of subscribing, browser, etc.). This will help you to prove in possible disputes that your actions were legal and you did not send emails without user’s consent.

Invalid recipients’ email addresses

The large number of invalid recipients will harm your reputation. You can reduce the amount of such recipients, if you use two-step subscription confirmation. Even if your recipients list will contain a few invalid email addresses, it will not harm your reputation.

There is the possibility that user’s email address from your recipients list will be blocked or deleted, for example, upon user’s request or due to an extended period of non-use. So that it is important to have monitoring mechanisms to check the existence and correctness of mail delivery to your recipients. If there is not such control, the reputation may deteriorate signficantly because of appearing of a  large number of invalid recipients.

The presence of more that 5% of invalid email addresses in mailings may lead to putting emails, sent from your domain, to ‘Spam’ folder or even to full blocking of all emails.

Users need to know who you are

Define your emails, so that users will not send them to ‘Spam’ by mistake. Make sure that ‘From’ field indicates a sender of an email clearly, and users will not confuse you with someone else – use your domain in the sender’s email address. Also indicate the name of your company or brand in a subject line. Even if users agreed to get your emails, they may not identify the origin of emails at first sight. Such subject lines as ‘Daily Newsletter from ‘Company’ or ‘Your monthly 'Product name' update’ will help users to recognize your emails immediately.

Even if you provide two-step subscription confirmation (confirmed opt-in), users may not recognize one of their subscriptions with a subject like ‘Buy two, get the third FREE!’. As a result, they may report such email as spam.

Different addresses for sending transactional and promotional emails

Do not send mass (promotional) emails from the same IP-address you use for regular or business correspondence, emails with important (technical or financial) information, etc. Separating your IPs and sender addresses for different types of tasks, you contribute to successful deliverability of your emails to recipients.

Warm up new domains and IP-addresses

In order to be protected from Spam, mail provider considers new senders (companies that send emails from previously unknown IP-address or domain) to be suspicious. Such companies do not have any reputation and mail provider does not know about users’ reaction to their mailings. That is why a good way to put new domain or IP-address into operation is to warm it up.

Warm up is a gradual increase of the amount of emails, which are sent through a domain/IP, with the aim of creating a good reputation. There is no ready-made formula to warm up new domain or sender’s IP-address. The quickness of increasing the amount of emails may depend on how long you collect and use subscribers’ database, on recipients’ involvement and loyalty and on many other factors. For example, if your current reputation leaves much to be desired, then changing or adding IP/domain will only exacerbate the situation. Also it is not recommended to change IP and domain at the same time, if possible.

You can learn more about commonly accepted recommendations here: Anti-Abuse Working Group's Senders Best Communications Practices Version 3.0 (Adobe Acrobat/PDF, in English).

We recommend you to start monitoring your mailings in real time by registering your domain with Postmaster It is a service, which was created specifically for mail senders, who want to improve not only the deliverability, but the quality of mailings as well.

Обновлено 3 июля 2021 г.
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