Mail — diagnostics and troubleshooting


451 domain.ru prohibited. Disk quota exceeded

It means that the disk space allocated for the domain has been exhausted.

Recommendations to sender:

Retry sending the message after some time. As a rule, the mail server retries automatically.

Recommendations for the recipient:

To resume receiving mail, you can:

  • Reallocate disk space in the Resources section of the hosting control panel.
  • Free up your domain’s mailboxes by deleting unnecessary messages.
  • Switch to a price plan with more disk space (followed by quota adjustment).

You can increase the quota of a specific mailbox in the control panel section Mail → Your domain → Your mailbox.

451 Please try another server

This message means that you need to retry connecting to another receiving server of Rucenter. If, after several attempts, message delivery still fails, the sender’s mail server settings must be adjusted:

  1. No response from the server mx02.nicmail.ru and a 4XX response from mx03.nicmail.ru should not be treated as a fatal error; delivery attempts must continue to the servers listed in the other MX records.
  2. The sending mail server connecting to Ru-Center servers must have correctly configured DNS records. A PTR record must exist for the mail server’s IP address in the reverse DNS zone. The value of the PTR record in the reverse zone must match the A record in the forward zone (i.e., the server name). Example: the outgoing mail server relay05.nicmail.ru has the IP address 194.85.88.236:

nslookup relay05.nicmail.ru
Non-authoritative answer:
Name: relay05.nicmail.ru
Address: 194.85.88.236

For this IP address, a PTR record exists in the reverse zone with the value relay05.nicmail.ru, matching the server name.

nslookup 194.85.88.236
Name: relay05.nicmail.ru
Address: 194.85.88.236

  1. The reverse DNS record must not contain words typical of dynamic IP addresses used by residential ISPs, such as:

broadband, pptp, dynamic, pool, ppp, peer, dhcp, cable, node, client, dialup, static, wanadoo, dsl, public, user, vpn.

  1. The timeout for waiting for responses from Rucenter servers must be at least 5 minutes in accordance with RFC 5321:
  • waiting at the connection stage (before receiving the 220 greeting): at least 5 minutes;
  • waiting after MAIL FROM: at least 5 minutes;
  • waiting after RCPT TO: at least 5 minutes.

452 message sending quota exceeded, try later

It means that the mailbox reached its limit for sending messages (50 letters per 15 minutes). The ability of sending letters will be resumed automatically within 10 minutes.

476 connections from your host are denied

It means that the connection from your IP address to hosting mail server is temporarily blocked. It occurs as a result of multiple errors during operation with mail server:

Blocking is lifted automatically within 15 minutes. To resolve the issue, we recommend checking that your mail client settings are correct. If the problem persists, please contact technical support by writing to support@nic.ru and include the following information in your message:

  • your agreement number,
  • the mailbox from which the sending attempt causes the issue;
  • your external IP address. You can find your external IP address on the websites http://myip.ru and http://2ip.ru

550 Your message was identified as SPAM

It means that incoming letter was identified as spam based on its contents analysis.

Recommendations to sender:

Try to change letter heading and try again. If the problem persists, please, contact the recipient by other means of communication with a request to add your domain to white list.

If you have no contact data of the recipient's registrant, use Whois service.

Recommendations to recipient:

You may add sender's domain to white list, then the mail from this domain will not pass spam filter. To add domain example.net to white list, it will be required to:

  • Log in to the hosting control panel using your agreement number and password.
  • Go to the Mail section.
  • click on name of mail domain;
  • go to Spam filter → Whitelist;
  • add a mask like *@example.net in the New email address mask field and click Create. 

550 mailbox@domain.ru prohibited. We do not relay

It means that address mailbox@domain.ru does not exist in Rucenter hosting mail system. Check spelling of address and try again.

591 mailbox@domain.ru You must authenticate first

It means that authorization is not set in mail client on the outbox mail server (SMTP) mail.nic.ru by box name and password (similar to inbox mail server).
We recommend to check correctness of mail client settings. For example, if you use Outlook, make sure that in your account settings for the outgoing mail server, the SMTP server requires authentication and Same as incoming mail server options are checked.

550 Sender domain does not match hosting account

This message indicates that the domain portion of the sender's address in the "FROM" header or "MAIL FROM" field of the email envelope is empty or contains a domain that is not added to your hosting service as a mail domain name or synonym.
We recommend checking the settings of your email client or other software that sends email and specifying the sender's address in a domain added to your hosting service.

550 Incorrect header syntax in From field

This message means that the From header containing the sender’s address includes information that does not comply with the requirements of RFC 5321 and RFC 5322.
In particular, if the From field contains a user name in addition to the email address, the name must be enclosed in quotation marks: From: "User Name" <username@example.net>

We recommend checking the settings of your mail client or other software used to send email, reviewing the text specified as the sender name, and enclosing it in quotation marks. In some mail clients, the use of quotation marks and special characters within the sender name (for example, "Ivan Ivanov, LLC "Romashka"") may cause an error. In such cases, it is recommended to remove quotation marks or special characters, and also consider updating the mail client.
 

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