General provisions

Opt-In. Recipients have explicitly expressed their desire to receive the information before it starts being distributed.

For example, use one of the following methods to ensure that you are sending mail to users who have unambiguously expressed their consent to receive it:

1. The user manually sets a "Subscribe..." checkbox The user registers or subscribes (we highly recommend against setting the subscribe checkbox by default);
2. The user sends a message with a request to subscribe to a special email address;
3. The user clicks on a link in an email confirming the subscription.

You must verify the user's email address before the subscription begins. The user must explicitly selected confirm that he/she is the owner of the email address. This can be done by sending an email with an activation code and instructions on how to confirm the email address. Additionally, in order to minimize the chance of being classified as spam, you should not acquire email address databases from third parties or collect address from other websites.

When users subscribe to your distribution, they should be informed as to what kind of communications they will receive, how often, and how they will appear. Be honest. Don't deceive your recipients!

Authentication 

Use DomainKeys Identified Mail (DKIM) authentication technology. This tool can provide you with a consistent reputation in terms of your domain, without being linked to the IP addresses you used to send your bulk mail.

Instructions on how to unsubscribe from the distribution 

Include complete and noticeable instructions on how to unsubscribe from the distribution in every email. Make the process of unsubscribing from your distribution as simple as possible. 

You must be sure that unsubscribing from your distribution is truly easy - for example, by simply clicking on a link in an email - and that the process does not require the user to perform complicated actions: entering or recovery a password, registration, etc. 

Users should not have to sign into a website in order to unsubscribe. The process of stopping a subscription or removing users from your database must happen without delay, immediately after the user expresses the desire that this be done.
 

Complaints about spam 

Many bulk mailers are blocked specifically due to users' complaints about spam, which are a result of the fact that users find it difficult to unsubscribe or remove themselves from a distribution's list of users, so they report spam.

We recommend saving all information about when a user subscribed to a distribution (IP address; date and time the subscription was made; browser, etc.) — In disputes, this will help you prove that your actions were proper and that you have not send emails without user consent.

Track your reputation in postmaster.mail.ru 
"Reputation" is feedback from users and represents the average percentage of complaints about your distributions (clicks on the "Spam" button in Mail's web interface).
Reputation is used by our filters to decide whether or not a message is spam. If you have a poor reputation, your mail distributions may entirely or partially blocked, or they may end up in users' Spam folder.
The following reputation values must not be exceeded (the lower your reputation, the better):

Messages per month	Reputation limit
up to 10,000	1.4%
up to 500,000	1.3%
up to 10,000,000	1.1%
up to 50,000,000	0.7%
over 50,000,000	0.4%

Non-existent email addresses 

A large number of invalid recipients will harm your reputation. You can reduce the number of such users in your distribution by using a two-step confirmation procedure to subscribe to your distribution. Your reputation won't be ruined if your list contains a few invalid email address. 

There is a chance that a user in your distribution will have his or her mailbox blocked or deleted, for example, at the user's request or due to an extended period of non-use. Therefore, it is important to have mechanisms to monitor the existence and correctness of mail delivery to your recipients. Without such a tracking mechanism, your reputation may worsen substantially over time due to a large increase in the number of invalid users.
 

The user must not be mistaken as to who you are 

Label your emails such that the user will not accidentally mistake them for spam. Be sure that the "From" field clearly indicates who sent the email and that the user won't confuse you with somebody else. Additionally, include the name of your company or brand in the email's subject. Even if users have agreed to receive your emails, they may not recognize who it came from at first glance. An email subject such as "ACME's Daily Newsletter" or "Your monthly 'Product name' update" will help users immediately recognize your emails.

Even if you provide a two-step confirmation process to subscribe to your distribution (confirmed opt-in), users may not recognize one of their subscriptions with a subject such as "Buy two, get the third FREE!". As a result, they may report this as spam.

Don't distribute mass (advertising) emails from the same IP address that you use for ordinary business correspondence, messages with important (technical or financial) information, etc. By dividing your IP address according to various tasks, you will ensure that your emails reliably reach their intended recipients.