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Description of Selectel mail service
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Description of Selectel mail service

Selectel Mail Service is a service for securely sending domain mailings from your servers in Selectel to external networks. You can send mail through the service only from servers in the Selectel infrastructure.

Principle of operation⁠

The service works as MTA (mail transfer agent) — sends mail from your servers to external networks. Information is transmitted in a secure form via TLS protocol, the service does not process mail data and does not save it. SMTP — Simple Mail Transfer Protocol is used for sending.

When you connect the service, a mail resource is created for you, to which you add your domain. You can add no more than three domains to the resource. For domains of one resource the same login and password will be used to connect to the SMTP server and common statistics will be collected.

After connecting the service, you send e-mails from your server to the service's mail node (SMTP relay). For sending you can use any utility that supports sending via SMTP. At the mail node the list of recipients is checked — addresses that are in the stop lists are excluded. The mail is then sent to the remaining recipients.

When sent, the service's technical headers are appended to the emails:

  • Return-Path — contains the technical mail sender@mail.selcloud.ru where delivery status messages are sent. If you need to specify your own mail in this field, create a ticket;
  • DKIM-Signature — confirms that the mail service has the right to make mailings on behalf of the domain, protects against spam.

Note the possible errors in the SMTP dialog.

Limitations⁠

The service has limits for the mail resource:

  • no more than one resource in a project;
  • no more than three domains in one resource;
  • speed of sending through the resource — 400 mails in 5 minutes regardless of the number of domains in the resource.

If you need to create more than one mail resource in a project, add more than three domains to a resource, or increase sending speed, create a ticket and describe the purpose of mailings. We will consider the possibility to increase the limits.

Only UTF-8 encoding is supported for emails.

The service has no restrictions on the number of newsletter recipients, email size or number of attachments.

We recommend:

  • Limit the weight of an email to no more than 10 MB. Mail services of recipients may reject e-mails with heavy weight as suspicious;
  • specify no more than five recipients in one e-mail. If at least one recipient is on the stop list, the email will not be sent to any of them.