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Errors in the SMTP dialog
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Errors in the SMTP dialog

The Selectel mail service uses the SMTP protocol. When sending mail from your server to the service's mail node, the following errors may occur in the SMTP dialog.

550 bounced check filterThe email address of one of the recipients is in the stop list. If more than one recipient is specified in the email, repeat the sending for each recipient separately to determine which of the addresses is on the stop list. If you think that the address was included in the stop list by mistake, remove it from the stop list using the [API method](https://developers.selectel.ru/docs/cloud-services/selectel-email-service-api /)
501 from domain not trustedThe domain from which the email is being sent has not been added to the list of allowed domains. To fix the error, create a ticket
421 SMTP command timeout — closing connectionThe server closed the connection because it had not been used for more than 120 seconds. To fix the error, start the SMTP dialog again

Stop list⁠

The recipient's email address is included in your local stop list if:

  • the recipient has unsubscribed from the mailing list;
  • the recipient complained about spam;
  • An email could not be sent to the email address.

Emails to email addresses from the stop list are not sent, the error 550 bounced check filter is returned in the SMTP dialog.

If you have specified several recipients in the email and at least one of the email addresses in the stop list, the email will not be sent to any of them. To determine which of the addresses is on the stop list, send an email separately to each of the recipients.

If you think that the address was included in the stop list by mistake, you can remove it from the stop list using the [API method](https://developers.selectel.ru/docs/cloud-services/selectel-email-service-api /).