Ниже вы можете узнать о возможных причинах сбоя при отправке почты.
Чаще всего ошибка с отправкой писем возникает в следующих случаях:
- Неверно указан адрес получателя. В данном случае вы получите обратное письмо о том, что данный почтовый ящик или домен не существует. (Ошибка 505)
- Превышены показатели ограничений на отправку. С ограничениями Вы можете ознакомиться на нашем сайте.
- Окончание почтовой квоты для данной э-почты. Решение проблемы вы сможете найти здесь.
- Ошибка в настройке почтовых клиентов. Проблема устраняется исправлением ошибок. С полными настройками для почтового клиента вы можете ознакомится здесь.
Самые распространенные ошибки в данном случае:
Error 503: valid rcpt command must precede data — требует подтвердить подлинность SMTP сервера. К примеру в Outlook это можно сделать поставив галочку напротив пункта «My server requires authentication» в настройках сервера исходящей почты.
Error 553 unable to verify address — так же требует подключить проверку подлинности SMTP сервера. Пожалуйста обратите внимание на то что в поле «Имя пользователя» необходимо ввести полный адрес электронной почты, к примеру [email protected].
You may see the following error messages and codes when using Gmail with Google Workspace . The messages and codes are helpful tools for diagnosing and troubleshooting email problems.
Gmail appends one or both of the following identifiers to all error messages to show you the source of the error:
- gsmtp (Google SMTP) is added to all errors.
- gcdp (Google Custom Domain Policies) is added to errors resulting from customized rules created by the administrator.
For example, «550 5.7.1 This message violates example.com email policy. — gcdp <sessionid> — gsmtp» indicates that the error is a result of a custom rule created by the administrator.
For more information, visit About SMTP error messages.
Note: Error #2014 is related to a Chrome browser extension. Disable your Chrome extensions one at a time to determine which extension is causing the error. The full text of error #2014 is: Oops… the system is experiencing a problem (#2014) — Try again.
SMTP error messages
| 421, «4.3.0», Temporary System Problem. Try again later |
| 421, «4.4.5», Server busy, try again later. |
| 421, «4.7.0», IP not in whitelist for RCPT domain, closing connection. |
| 421, «4.7.0», Our system has detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been temporarily blocked. For more information, visit Prevent mail to Gmail users from being blocked or sent to spam. |
| 421, «4.7.0», Temporary System Problem. Try again later. |
| 421, «4.7.0», TLS required for RCPT domain, closing connection. |
| 421, «4.7.0», Try again later, closing connection. This usually indicates a Denial of Service (DoS) for the SMTP relay at the HELO stage. |
| 450, «4.2.1» The user you are trying to contact is receiving mail too quickly. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, visit Limits for sending & getting mail. |
| 450, «4.2.1», The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. Please resend your message at a later time. If the user is able to receive mail at that time, your message will be delivered. For more information, visit Limits for sending & getting mail. |
| 450, «4.2.1», Peak SMTP relay limit exceeded for customer. This is a temporary error. For more information on SMTP relay limits, please contact your administrator or visit SMTP relay service error messages. |
| 451, «4.3.0», Mail server temporarily rejected message. |
| 451, «4.3.0», Multiple destination domains per transaction is unsupported. Please try again. |
| 451, «4.4.2», Timeout — closing connection. |
| 451, «4.5.0», SMTP protocol violation, visit RFC 2821. |
| 452, «4.2.2», The email account that you tried to reach is over quota. Please direct the recipient to Clear Google Drive space & increase storage. |
|
452, «4.5.3», Domain policy size per transaction exceeded, please try this recipient in a separate transaction. |
| 452, «4.5.3», Your message has too many recipients. For more information regarding Google’s sending limits, visit Limits for sending & getting mail. |
| 454, «4.5.0», SMTP protocol violation, no commands allowed to pipeline after STARTTLS, visit RFC 3207. |
| 454, «4.7.0», Cannot authenticate due to temporary system problem. Try again later. |
| 454, «5.5.1», STARTTLS may not be repeated. |
| 501, «5.5.2», Cannot Decode response. |
| 501, «5.5.4», HELO/EHLO argument is invalid. For more information, visit HELO/EHLO email error. |
| 502, «5.5.1», Too many unrecognized commands, goodbye. |
| 502, «5.5.1», Unimplemented command. |
| 502, «5.5.1», Unrecognized command. |
| 503, «5.5.1», «EHLO/HELO first. |
| 503, «5.5.1», MAIL first. |
| 503, «5.5.1», RCPT first. |
| 503, «5.7.0», No identity changes permitted. |
| 504, «5.7.4», Unrecognized Authentication Type. |
| 530, «5.5.1», Authentication Required. For more information, visit Can’t sign in to your Google Account. |
| 530, «5.7.0», Must issue a STARTTLS command first. |
| 535, «5.5.4», Optional Argument not permitted for that AUTH mode. |
| 535, «5.7.1», Application-specific password required. For more information, visit Sign in using App Passwords. |
| 535, «5.7.1», Please log in with your web browser and then try again. For more information, visit Check Gmail through other email platforms. |
| 535, «5.7.1», Username and Password not accepted. For more information, visit Can’t sign in to your Google Account. |
| 550, «5.1.1», The email account that you tried to reach does not exist. Please try double-checking the recipient’s email address for typos or unnecessary spaces. For more information, visit Fix bounced or rejected emails. |
| 550, «5.2.1», The email account that you tried to reach is disabled. |
| 550, «5.2.1», The user you are trying to contact is receiving mail at a rate that prevents additional messages from being delivered. For more information, visit Limits for sending & getting mail. |
| 550, «5.4.5», Daily sending quota exceeded. For more information, visit Email sending limits. |
| 550, «5.4.5», Daily SMTP relay limit exceeded for user. For more information on SMTP relay sending limits please contact your administrator or visit SMTP relay service error messages. |
| 550, «5.7.0», Mail relay denied. |
| 550, «5.7.0», Mail Sending denied. This error occurs if the sender account is disabled or not registered within your Google Workspace domain. |
| 550, «5.7.1», Email quota exceeded. |
| 550, «5.7.1», Invalid credentials for relay. |
| 550, «5.7.1», Our system has detected an unusual rate of unsolicited mail originating from your IP address. To protect our users from spam, mail sent from your IP address has been blocked. Review Prevent mail to Gmail users from being blocked or sent to spam. |
| 550, «5.7.1», Our system has detected that this message is likely unsolicited mail. To reduce the amount of spam sent to Gmail, this message has been blocked. For more information, visit Why has Gmail blocked my messages? |
| 550, «5.7.1», The IP you’re using to send mail is not authorized to send email directly to our servers. Please use the SMTP relay at your service provider instead. For more information, visit ‘The IP you’re using to send email is not authorized…’. |
| 550, «5.7.1», The user or domain that you are sending to (or from) has a policy that prohibited the mail that you sent. Please contact your domain administrator for further details. For more information, visit Sorry, a policy is in place that prevents your message from being sent. |
| 550, «5.7.1», Unauthenticated email is not accepted from this domain. |
| 550, «5.7.1», Daily SMTP relay limit exceeded for customer. For more information on SMTP relay sending limits please contact your administrator or visit SMTP relay service error messages. |
| 550, «5.7.26», » Unauthenticated email from domain-name is not accepted due to domain’s DMARC policy. Please contact the administrator of domain-name domain. If this was a legitimate mail please visit Control unauthenticated mail from your domain to learn about the DMARC initiative. If the messages are valid and aren’t spam, contact the administrator of the receiving mail server to determine why your outgoing messages don’t pass authentication checks. |
|
550, «5.7.26», «This message does not have authentication information or fails to pass authentication checks (SPF or DKIM). To best protect our users from spam, the message has been blocked. Please visit Prevent mail to Gmail users from being blocked or sent to spam for more information.» |
| 550, «5.7.26», «This message fails to pass SPF checks for an SPF record with a hard fail policy (-all). To best protect our users from spam and phishing, the message has been blocked. Please visit Prevent mail to Gmail users from being blocked or sent to spam for more information.» |
| 552, «5.2.2», The email account that you tried to reach is over quota. |
| 552, «5.2.3», Your message exceeded Google’s message size limits. For more information, visit Send attachments with your Gmail message. |
| 553, «5.1.2», We weren’t able to find the recipient domain. Please check for any spelling errors, and make sure you didn’t enter any spaces, periods, or other punctuation after the recipient’s email address. |
| 554, «5.6.0», Mail message is malformed. Not accepted. |
| 554, «5.6.0», Message exceeded 50 hops, this may indicate a mail loop. |
| 554, «5.7.0», Too Many Unauthenticated commands. |
| 555, «5.5.2», Syntax error. |
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SMTP Server Response Codes |
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SMTP servers use to respond to commands using a defined set of codes. This page is a small guide to the codes mail servers may produce when you try to send mail along with their meanings. They are part of the SMTP protocol (the set of rules used to send emails).
1: The server has accepted the command, but does not yet take action. A confirmation message is required. 2: The server has completed the task successfully. 3: The server has understood the request, but requires further information to complete it. 4: The server has encountered a temporary failure. If the command is repeated without any change, it might be completed. 5: The server has encountered an error.
0: A syntax error has occured. 1: Indicates a informational reply, for example to a HELP request. 2: Refers to the connection status. 3 and 4 are unspecified. 5: Refers to the status of the mail system as a whole and the mail server in particular.
This leads us to the detailed list of ESMTP server response codes, as layed down in RFC 821 and later extensions.
▸ Blue rows correspond to successfull responses. |
The first generally tells whether the server accepted the command and if it could handle it. The five possible values are:| MaxBulk Mailer is a full-featured and easy-to-use bulk mailer and mail-merge software for macOS and Windows that allows you to send out customized press releases, prices lists, newsletters and any kind of text or HTML documents to your customers or contacts.
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When your transactional emails fail to get delivered, you might have an SMTP error notification that needs to be addressed. Read on to learn about common SMTP response codes and how you can troubleshoot delivery issues.
Simple Mail Transfer Protocol (SMTP) is the standard communication protocol for sending emails over the Internet.
Getting started with SMTP for your transactional emails is quick and easy. You provide your server name, SMTP port, username and password and the SMTP server then sends emails on your behalf and takes care of email deliverability.
However, SMTP errors can prevent your emails from getting delivered. And when these problems occur, it’s difficult to understand the cryptic error codes in your delivery reports. In this article, you’ll learn how to read common SMTP response codes and how you can troubleshoot delivery errors.
Looking for an SMTP service?
Learn more about MailerSend’s SMTP relay.
SMTP response codes are updates sent by an SMTP server during the mail delivery process. Using a 3-digit format, they are sent in response to commands issued by an SMTP client. These numerical codes indicate a status or error pertaining to a message transmission, allowing senders to troubleshoot sending issues.
The following diagram shows the relationship between the SMTP client and server in the mail delivery process.
Common SMTP codes and how to troubleshoot them
The current SMTP standard defines the response codes but they are applied differently between SMTP servers. Not every mail server is configured in the same way and thus there will be differences in how mail delivery failures are interpreted.
Remember:
Because no two SMTP servers are alike, a “mailbox unavailable” response on one server may be a “message rejected” error on another!
General SMTP status codes
SMTP codes that start with 2 and 3 are general status messages that are sent in reply to requests from the sending server. They do not indicate errors in the mail delivery but are used as prompts in the exchange between the mail servers.
|
SMTP code |
Description |
Meaning |
|
214 |
Help message |
A response to the HELP command that usually includes a link or URL to the FAQ page. |
|
220 |
SMTP Service ready |
The receiving server is ready for the next command. |
|
221 |
Service closing transmission channel |
The receiving server is closing the SMTP connection. |
|
235 |
2.7.0 Authentication succeeded |
The sending server’s authentication is successful. |
|
250 |
Requested mail action okay, completed |
Success! The email was delivered. |
|
251 |
User not local; will forward to <forward-path> |
The receiving server doesn’t recognize the recipient but it will forward it to another email address. |
|
252 |
Cannot VRFY user, but will accept message and attempt delivery |
The receiving server doesn’t recognize the recipient but it will try to deliver the email anyway. |
|
334 |
Reponse to email authentication AUTH command when the authentication method is accepted |
Authentication has been successful. |
|
354 |
Start mail input |
The email “header” has been received, the server is now waiting for the “body” of the message. |
Temporary SMTP error codes
SMTP 400 codes are transient errors and are usually related to issues at the receiving mail server. Messages are returned as a soft bounce and the sender may try again after, for example, reducing the size of the attachments in the email.
|
SMTP code |
Description |
Meaning |
|
421 |
Service not available, closing transmission channel |
The receiving server or sending server is not reachable but another mail delivery will be attempted. If you are using a remote server like MailerSend’s SMTP relay to send emails, test that you can connect to it successfully. Otherwise, you may wish to check the receiving server’s availability. |
|
450 |
Requested mail action not taken: mailbox unavailable |
This error could mean that the recipient does not exist, the mailbox does not have permission to receive the email, or the message was rejected due to a blocklist or filter. To fix this, you should confirm the recipient’s email address, see if your IP address is on a blocklist, test your email for spam-like content, or try sending an email without an attachment. |
|
451 |
Requested action aborted: error in processing |
The receiving server is unable to process the message due to email authentication rules. For example, if Sender Policy Framework (SPF) is being used, you should confirm that a DNS lookup can be made for your sending domain and that the domain’s name server is functioning properly. |
|
452 |
Requested action not taken: insufficient system storage |
The receiving server is overwhelmed by too many messages being sent at once or is out of memory or storage space. Review your sending rate by looking at your mail-sending queue and logs, or inform the server’s mail administrator about the storage and free memory issues. |
|
455 |
Server unable to accommodate the parameters |
The server cannot process the command at this time. You can retry after waiting a while or contact the receiving server’s mail administrator if the error persists. |
Permanent SMTP error codes
SMTP 500 reply codes are mail delivery errors of a permanent nature that are usually caused by the sender. The receiving server returns the message as a hard bounce and prefers that the sender not try again unless the problem is fixed.
The 500 series starts with errors in issuing SMTP commands like the following examples:
|
SMTP code |
Description |
Meaning |
|
500 |
Syntax error, command unrecognized |
The receiving server does not recognize the command. If your server is using antivirus or firewall software, try disabling them before sending the message again. |
|
501 |
Syntax error in parameters or arguments |
The command is recognized but there are errors with its options or command arguments. This server error is sometimes returned for an invalid or incorrect email! But it may be due to your antivirus or firewall software as well. |
|
502 |
Command not implemented |
The command is currently not supported on the receiving server. Review your sending commands as well as your MTA’s configuration. |
|
503 |
Bad sequence of commands |
The receiving server recognizes the command but its parameters or options are in the wrong sequence. This sometimes appears when the email account is not authenticated. Do review your MTA’s configuration as well. |
|
504 |
Command parameter not implemented |
Similar to 502, the command is recognized but its parameters or options are not supported on the receiving server. You may wish to review your sending commands as well as your MTA’s configuration. |
|
521 |
Server does not accept mail |
The server does not receive or send mail. This may be because the server is part of a mail relay. The email may fail or be relayed to another mail server. Check if the email has been delivered to confirm. |
The SMTP error codes then get more serious, like being suspected of sending spam or appearing in a blocklist. As an email sender, you should pay attention to the following codes because they can affect your sending reputation and email deliverability.
|
SMTP code |
Description |
Meaning |
|
535 |
Authentication credentials are invalid |
There is an issue with client authentication with the email server. This may be because of incorrect credentials, invalid authentication methods, or invalid encryption settings. |
|
541 |
The recipient address rejected your message |
The mail from the sender has been flagged as spam or blocked by the receiving server’s rules. Find out if your IP address is in a blocklist and scan your emails for content that could trigger spam filters. If you’re clear, ask the administrator of the server to put you on their safelist. |
|
550 |
Requested action not taken: mailbox unavailable |
The recipient’s email address does not exist. Verify the email address by making sure it is free of typos or use an email verification tool like MailerSend’s inbuilt feature. Error code 550 is sometimes used as a generic error code and it can also appear as 550 Blocked error or 550 Invalid recipient depending on the server’s configuration. If you get the blocked error message, check to see if your IP address is in a blocklist. |
|
551 |
User not local; please try <forward-path> |
The recipient was not found on the server but the message will be forwarded to another email. Used for spam prevention, this error is shown when you are not authorized to relay mail through the server. Review your authentication records to see if you can use an SMTP relay. |
|
552 |
Requested mail action aborted: exceeded storage allocation |
The user’s mailbox is full! Besides waiting for messages to be deleted, you can try to contact them through other means and inform them that their inbox is full. |
|
553 |
Requested action not taken: mailbox name not allowed |
The recipient cannot be found due to errors in the email address. Check that the email addresses are correct in the To, Cc and Bcc fields. |
|
554 |
Transaction failed |
This is bad news! The receiving mail server will not accept your message because, for example, you’re on a blocklist. Confirm whether your IP address appears in a blocklist. If you’re good, send a request to the receiving server to put your IP in their safelist. |
Bonus: How to read SMTP codes
The SMTP specification defined basic status codes that were published in 1982. Because the codes were originally designed to report on the outcome of an SMTP command, their lack of detail made them unsuitable for delivery reports.
To make things more complicated, some servers would assign the same error code to different delivery failures. Others would assign a code that only explained its meaning in the text description. Inconsistent application of the codes meant it was difficult to resolve mail sending issues!
Enter the enhanced status codes. They extend the basic status codes by providing more detail about the cause of the email delivery failure. Similarly, they also consist of 3-digit numbers separated by decimals. Let’s take a look at how to read them next.
Basic status codes
The first digit of a basic status code tells the sending server whether the response is good, bad or incomplete:
|
Code |
Description |
Meaning |
|
2 |
Positive Completion Reply |
The requested action has been successfully completed. |
|
3 |
Positive Intermediate Reply |
The command is accepted but more information is needed before proceeding. |
|
4 |
Transient Negative Completion Reply |
The command was not accepted and no action was taken. This error is seen as temporary (soft bounce) and the sender can try again later. |
|
5 |
Permanent Negative Completion Reply |
The command was not accepted and no action was taken. This is a permanent error (hard bounce) and the sender should not repeat the command. |
The second digit puts the SMTP response into a specific category:
|
Code |
Description |
Meaning |
|
0 |
Syntax |
Responses about commands or parameters. |
|
1 |
Information |
Responses to requests for more information. |
|
2 |
Connections |
Responses about the transmission channel. |
|
5 |
Mail system |
Responses about the status of the receiving mail server. |
The third digit goes into more detail within the response category.
For example, if you telnet to MailerSend’s SMTP server and introduce yourself with the HELO command, you will see the following exchange:
HELO mailersend.net
250 smtp.mailersend.net Nice to meet you, [8.38.148.103]The 250 response code means that it is a positive completion reply about the status of the mail system, i.e. the SMTP server has acknowledged your IP address and is waiting for your next command.
Enhanced status codes
Like the basic status codes, the first digit defines the class to which the code belongs:
|
Code |
Description |
Meaning |
|
2 |
Success |
The requested mail action is okay and completed. |
|
4 |
Persistent Transient Failure |
Temporary conditions will cause the message to be delayed or abandoned. |
|
5 |
Permanent Failure |
The message in its current form cannot be delivered. |
The second digit identifies the subject of the SMTP reply code:
|
Code |
Subject |
|
0 |
Other or Undefined Status |
|
1 |
Addressing Status |
|
2 |
Mailbox Status |
|
3 |
Mail System Status |
|
4 |
Network and Routing Status |
|
5 |
Mail Delivery Protocol Status |
|
6 |
Message Content or Media Status |
|
7 |
Security or Policy Status |
Finally, the third digit provides more detail and depends on the class and the subject.
For example, if you specify the recipient of the email with the RCPT TO command, the SMTP server may respond with 250 2.1.5 Recipient OK. This code means that not only is your command successful, but the address of the recipient at the server has also been accepted.
SMTP response codes deciphered
SMTP plays a critical role in the email infrastructure of the Internet. It’s easy to implement it in your technology stack, but when things go wrong it’s hard to decipher what those SMTP codes mean. Here’s a tip: Bookmark this page and return to it whenever you encounter one!
What are the most common SMTP error codes that you’ve come across? Tell us about it below!
Looking for an email service that makes SMTP super simple?
Sign up to MailerSend for free to start using our SMTP relay, webhooks, advanced email editors and more.
Если вы не используете сервис рассылки для отправки писем, они могут не попасть во «Входящие» получателей из-за SMTP ошибок. Отправляйте письма через SMTP сервис SendPulse. Мы предлагаем чистые IP адреса, надежные серверы, SPF и DKIM записи, чтобы повысить доставляемость ваших рассылок. А узнать о значениях и причинах SMTP ошибок вы можете в этой статье.
Код ошибки — это зашифрованная комбинация чисел, которая требует объяснения. Чтобы понять, почему ваше письмо не может быть отправлено, обязательно нужно знать значение кода ошибки.
Код SMTP ошибок состоит из 3 цифр, каждая из которых имеет свое значение.
Первая цифра указывает на то, был ли принят и обработан ваш запрос.
Существует 5 значений для первой цифры кода SMTP ошибки
- Сервер принял команду, но не предпринял никаких действий, так как ожидает подтверждения на выполнение запрашиваемых действий.
- Действие было успешно выполнено и сервер готов принимать новую команду.
- Сервер принял команду, но для её завершения требуется дополнительная информация.
- Возник временный сбой. Если не последует изменений при повторении команды, попробуйте ещё раз.
- Сервер столкнулся с неустранимой ошибкой, ваша команда не будет обработана.
Если код начинается с цифры 2 — ваша команда успешно обработана, если с 4 — есть временный сбой, с 5 — постоянный сбой. В последнем случае ваши письма не будут отправлены, пока вы не устраните ошибку.
Существует 4 значения для второй цифры кода SMTP ошибки
- Синтаксическая ошибка.
- Информационный ответ (запрос информации, например, помощь).
- Обозначает состояние подключения.
- Обозначает состояние почтового сервера или почтовой системы.
Последняя цифра в коде несет более подробную информацию о статусе доставки.
Самые важные коды SMTP ошибок
214 — Ответ на запрос информации о том, как работать с сервером, описание нестандартных команд, полезное только для человека.
220 — Готов к работе.
221 — Служба обслуживает заключительный канал передачи данных.
250 — Запрашиваемое почтовое действие успешно завершено.
251 — Получатель не местный, но сервер переотправит письмо.
252 — Почтовый ящик не может быть верифицирован сервером, но он будет осуществлять попытки доставить письмо.
354 — Начинайте ввод сообщения. Оно должно заканчиваться точкой на новой строке.
421 — Сервер недоступен, канал связи будет закрыт.
422 — Размер письма превышает лимит входящих сообщений получателя.
442 — Почтовый сервер начал доставлять письмо, но подключение было прервано во время передачи.
450 — Запрашиваемое действие не было выполнено, почтовый ящик был недоступен. Он может быть временно занят.
451 — Запрашиваемое действие было прервано, локальная ошибка во время обработки.
452 — Запрашиваемое действие не выполнено: недостаточно места в системе.
500 — Синтаксическая ошибка, потому что серверу не удалось распознать команду. Это может быть слишком длинная командная строка.
501 — Синтаксическая ошибка в параметрах или аргументах. Это может быть неправильный адрес электронной почты.
502 — Команда нереализована. Она валидна, но не активирована вашим провайдером.
503 — Неверная последовательность команд, почтовый сервер требует аутентификацию.
504 — Параметр команды не реализован.
510 — Неверный адрес электронной почты. Адреса ваших получателей могут содержать ошибки.
512 — Домен получателя не найден или не существует.
513 — Неверный адрес электронной почты. Может содержать ошибки, или сервер требует аутентификацию.
515 — Неверный адрес электронной почты.
521 — Почтовый ящик не принимает письма.
523 — Размер письма превышает лимит почтового ящика получателя.
530 — Требуется аутентификация, или сервер получателя добавил вас в черный список. Это может быть и неверный адрес электронной почты.
531 — Почтовая система заполнена.
534 — Недостаточно надежный механизм аутентификации.
535 — Ошибки аутентификации.
541 — Почтовый ящик получателя отметил ваше письмо как спам.
550 — Запрашиваемые действия не выполнены, потому что почтовый ящик недоступен. Команда могла быть отклонена политикой безопасности, или почтовый ящик не был найден.
551 — Нелокальный пользователь или неверный адрес электронной почты.
552 — Запрашиваемое действие прервано из-за превышения дискового пространства.
553 — Запрашиваемое действие не выполнено, возможна синтаксическая ошибка в имени почтового ящика.
554 — Передача данных не удалась. Так случается, если сервер получателя считает ваше письмо спамом, находит ваш IP адрес в черном списке, или сам добавляет его в свой черный список.
555 — Адрес электронной почты не был опознан сервером.
SMTP для email рассылок
Забудьте об SMTP ошибках! Мы позаботимся о технической стороне рассылок, чтобы вы могли сконцентрироваться на маркетинговой стратегии.
- Выделенный IP адрес не позволит попадать в черные списки, ведь репутация отправителя будет зависеть только от вас.
- Криптографические подписи DKIM и SPF помогут подтвердить подлинность вашего домена и минимизируют количество писем, попадающих в спам.
Мы оставляем свои подписи на всех исходящих сообщениях по умолчанию, что улучшает доставляемость писем.
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Обновлено: 27.02.2023