{"id":869,"date":"2025-12-19T10:06:20","date_gmt":"2025-12-19T09:06:20","guid":{"rendered":"https:\/\/mybox.com\/help\/?post_type=manual_kb&#038;p=869"},"modified":"2026-06-25T08:48:13","modified_gmt":"2026-06-25T06:48:13","slug":"coduri-de-eroare-smtp-si-o-lista-de-coduri-cu-explicatii","status":"publish","type":"manual_kb","link":"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/","title":{"rendered":"Codurile de eroare SMTP \u0219i semnifica\u021bia lor"},"content":{"rendered":"<div class=\"translation-block translation-block-merged\">\n<p class=\"wp-block-paragraph\">When an email cannot be delivered successfully, the sending mail server typically returns an SMTP error code. These codes help identify the reason for the delivery failure and can be useful when troubleshooting email issues.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">SMTP error codes usually consist of three digits, sometimes followed by an extended status code such as:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>554 5.7.1\n<\/code><\/pre>\n\n\n\n<div id=\"ez-toc-container\" class=\"ez-toc-v2_0_86 ez-toc-wrap-left counter-hierarchy ez-toc-counter ez-toc-custom ez-toc-container-direction\">\n<div class=\"ez-toc-title-container\">\n<p class=\"ez-toc-title\" style=\"cursor:inherit\">Table of Contents<\/p>\n<span class=\"ez-toc-title-toggle\"><\/span><\/div>\n<nav><ul class='ez-toc-list ez-toc-list-level-1' ><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-1\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Contents\" >Contents<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Understanding_SMTP_Status_Codes\" >Understanding SMTP Status Codes<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#First_Digit\" >First Digit<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Second_Digit\" >Second Digit<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Third_Digit\" >Third Digit<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-6\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Common_554_571_Errors\" >Common 554 5.7.1 Errors<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-7\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#SMTP_Error_Code_Reference\" >SMTP Error Code Reference<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-8\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Success_and_Informational_Codes\" >Success and Informational Codes<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-9\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Temporary_Failures_4xx\" >Temporary Failures (4xx)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-10\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Permanent_Failures_5xx\" >Permanent Failures (5xx)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-11\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Address_and_Recipient_Errors_51x\" >Address and Recipient Errors (51x)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-12\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Message_Size_Errors_52x\" >Message Size Errors (52x)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-13\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Mail_System_Errors_53x\" >Mail System Errors (53x)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-14\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Routing_and_DNS_Errors_54x\" >Routing and DNS Errors (54x)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-15\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Mailbox_and_Delivery_Errors_55x\" >Mailbox and Delivery Errors (55x)<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-16\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Security_and_Policy_Errors_56x%E2%80%9357x\" >Security and Policy Errors (56x\u201357x)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-17\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Troubleshooting_Tips\" >Troubleshooting Tips<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-18\" href=\"https:\/\/mybox.com\/help\/ro\/knowledgebase\/smtp-error-codes-and-a-list-of-codes-with-explanations\/#Summary\" >Summary<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Contents\"><\/span>Contents<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Understanding SMTP Status Codes<\/li>\n\n\n\n<li>Common 554 5.7.1 Errors<\/li>\n\n\n\n<li>SMTP Error Code Reference<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Understanding_SMTP_Status_Codes\"><\/span>Understanding SMTP Status Codes<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"First_Digit\"><\/span>First Digit<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<\/div>\n\n<div id=\"mybox-2128820284\" class=\"mybox-content mybox-entity-placement\"><div class=\"early-access-banner-inpost\">\r\n  <div class=\"banner-left-inpost\">\r\n    <div class=\"icon-box-inpost\">\r\n      <img decoding=\"async\" src=\"https:\/\/mybox.com\/help\/wp-content\/uploads\/2026\/02\/square-info-icon.svg\" alt=\"Info\">\r\n    <\/div>\r\n    <div class=\"text-box-inpost\">\r\n      <span class=\"label-inpost\"><span class=\"translation-block translation-block-banner-text\">Acces timpuriu<\/span><\/span>\r\n      <h4><span class=\"translation-block translation-block-banner-text\">Mai ave\u021bi nevoie de ajutor?<\/span><\/h4>\r\n      <p><span class=\"translation-block translation-block-banner-text\">Contacta\u021bi echipa noastr\u0103 de servicii pentru clien\u021bi.<\/span><\/p>\r\n    <\/div>\r\n  <\/div>\r\n\r\n  <div class=\"banner-right-inpost\">\r\n    <a href=\"https:\/\/panel.mybox.com\/helpdesk2\/v\/list\/\" class=\"banner-button-inpost\"><span class=\"translation-block translation-block-banner-text\">Trimite mesaj<\/span><\/a>\r\n  <\/div>\r\n<\/div><\/div>\n\n<div class=\"translation-block translation-block-merged\"><p class=\"wp-block-paragraph\">The first digit indicates the overall result of the command.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Meaning<\/th><\/tr><\/thead><tbody><tr><td>1xx<\/td><td>Command accepted, but additional confirmation is required (rarely used)<\/td><\/tr><tr><td>2xx<\/td><td>Success \u2013 the requested action completed successfully<\/td><\/tr><tr><td>3xx<\/td><td>Additional information is required<\/td><\/tr><tr><td>4xx<\/td><td>Temporary failure \u2013 retrying later may succeed<\/td><\/tr><tr><td>5xx<\/td><td>Permanent failure \u2013 the action could not be completed<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Second_Digit\"><\/span>Second Digit<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The second digit provides additional information about the category of the response.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Meaning<\/th><\/tr><\/thead><tbody><tr><td>x0x<\/td><td>Syntax-related status<\/td><\/tr><tr><td>x1x<\/td><td>Informational response<\/td><\/tr><tr><td>x2x<\/td><td>Connection status<\/td><\/tr><tr><td>x3x<\/td><td>Reserved<\/td><\/tr><tr><td>x4x<\/td><td>Reserved<\/td><\/tr><tr><td>x5x<\/td><td>Mail system status<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Third_Digit\"><\/span>Third Digit<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">The third digit provides more specific information about the error condition.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Common_554_571_Errors\"><\/span>Common 554 5.7.1 Errors<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">The status code:<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>554 5.7.1\n<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">is one of the most frequently encountered SMTP delivery errors and generally indicates a permissions, authentication, or anti-spam issue.<\/p>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Error Message<\/th><th>Explanation<\/th><\/tr><\/thead><tbody><tr><td>Delivery not authorized<\/td><td>Message delivery was not authorized.<\/td><\/tr><tr><td>You are not allowed to connect<\/td><td>Connection to the server was refused.<\/td><\/tr><tr><td>Client host rejected: Access denied<\/td><td>The sending host has been blocked.<\/td><\/tr><tr><td>Service unavailable; Client host blocked<\/td><td>The sender&#8217;s server has been denied access.<\/td><\/tr><tr><td>Relay access denied<\/td><td>Relaying through the server is not permitted.<\/td><\/tr><tr><td>Recipient address rejected: Access denied<\/td><td>The recipient address was rejected.<\/td><\/tr><tr><td>Message cannot be accepted, rules rejection<\/td><td>Server rules prevented delivery.<\/td><\/tr><tr><td>Message refused by Dictionary check<\/td><td>Message was rejected by content filtering.<\/td><\/tr><tr><td>Relay Access Denied for One Domain<\/td><td>Relaying is not allowed for the specified domain.<\/td><\/tr><tr><td>Message cannot be accepted, spam rejection<\/td><td>Message was identified as possible spam.<\/td><\/tr><tr><td>Message refused by DNSBL check<\/td><td>Sending IP address appears on a blacklist.<\/td><\/tr><tr><td>Sender address rejected: Access denied<\/td><td>Sender address was not authorized.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"SMTP_Error_Code_Reference\"><\/span>SMTP Error Code Reference<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Success_and_Informational_Codes\"><\/span>Success and Informational Codes<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>211<\/td><td>System status message<\/td><\/tr><tr><td>214<\/td><td>Help message<\/td><\/tr><tr><td>220<\/td><td>SMTP service ready<\/td><\/tr><tr><td>221<\/td><td>SMTP service closing connection<\/td><\/tr><tr><td>250<\/td><td>Requested action completed successfully<\/td><\/tr><tr><td>251<\/td><td>Recipient is not local, message will be forwarded<\/td><\/tr><tr><td>252<\/td><td>Recipient cannot be verified, delivery will be attempted<\/td><\/tr><tr><td>354<\/td><td>Server ready to receive message content<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Temporary_Failures_4xx\"><\/span>Temporary Failures (4xx)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>421<\/td><td>Service unavailable, connection closed<\/td><\/tr><tr><td>422<\/td><td>Mailbox quota exceeded<\/td><\/tr><tr><td>431<\/td><td>Insufficient storage space<\/td><\/tr><tr><td>432<\/td><td>Delivery queue temporarily frozen<\/td><\/tr><tr><td>441<\/td><td>Network connection interrupted<\/td><\/tr><tr><td>442<\/td><td>Connection lost during delivery<\/td><\/tr><tr><td>446<\/td><td>Too many delivery hops detected<\/td><\/tr><tr><td>447<\/td><td>Connection timeout<\/td><\/tr><tr><td>449<\/td><td>DNS configuration issue<\/td><\/tr><tr><td>450<\/td><td>Mailbox unavailable<\/td><\/tr><tr><td>451<\/td><td>Temporary server error<\/td><\/tr><tr><td>452<\/td><td>Insufficient server resources<\/td><\/tr><tr><td>465<\/td><td>Language or character encoding issue<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Permanent_Failures_5xx\"><\/span>Permanent Failures (5xx)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>500<\/td><td>Syntax error, command not recognized<\/td><\/tr><tr><td>501<\/td><td>Syntax error in command parameters<\/td><\/tr><tr><td>502<\/td><td>Command not implemented<\/td><\/tr><tr><td>503<\/td><td>Bad command sequence<\/td><\/tr><tr><td>504<\/td><td>Command parameter not implemented<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Address_and_Recipient_Errors_51x\"><\/span>Address and Recipient Errors (51x)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>510<\/td><td>Invalid recipient address<\/td><\/tr><tr><td>511<\/td><td>Recipient address problem<\/td><\/tr><tr><td>512<\/td><td>Hostname not found<\/td><\/tr><tr><td>513<\/td><td>Missing or invalid address field<\/td><\/tr><tr><td>514<\/td><td>Duplicate address conflict<\/td><\/tr><tr><td>515<\/td><td>Invalid destination mailbox<\/td><\/tr><tr><td>516<\/td><td>Mailbox may have been moved<\/td><\/tr><tr><td>517<\/td><td>Sender address problem<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Message_Size_Errors_52x\"><\/span>Message Size Errors (52x)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>521<\/td><td>Message too large<\/td><\/tr><tr><td>522<\/td><td>Recipient mailbox quota exceeded<\/td><\/tr><tr><td>523<\/td><td>Message exceeds recipient size limits<\/td><\/tr><tr><td>524<\/td><td>Distribution list processing problem<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Mail_System_Errors_53x\"><\/span>Mail System Errors (53x)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>530<\/td><td>Mail transport service issue<\/td><\/tr><tr><td>531<\/td><td>Mail system storage full<\/td><\/tr><tr><td>532<\/td><td>System temporarily not accepting mail<\/td><\/tr><tr><td>533<\/td><td>Insufficient disk space on destination server<\/td><\/tr><tr><td>534<\/td><td>Message too large<\/td><\/tr><tr><td>535<\/td><td>Mail routing loop detected<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Routing_and_DNS_Errors_54x\"><\/span>Routing and DNS Errors (54x)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>540<\/td><td>DNS resolution problem<\/td><\/tr><tr><td>541<\/td><td>No response from destination host<\/td><\/tr><tr><td>542<\/td><td>Connection problem<\/td><\/tr><tr><td>543<\/td><td>Routing failure<\/td><\/tr><tr><td>544<\/td><td>Next routing hop unavailable<\/td><\/tr><tr><td>546<\/td><td>Mail loop detected<\/td><\/tr><tr><td>547<\/td><td>Delivery timeout<\/td><\/tr><tr><td>548<\/td><td>Recipient policy restriction<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Mailbox_and_Delivery_Errors_55x\"><\/span>Mailbox and Delivery Errors (55x)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>550<\/td><td>Mailbox unavailable or message rejected<\/td><\/tr><tr><td>551<\/td><td>Recipient not local; forwarding address provided<\/td><\/tr><tr><td>552<\/td><td>Storage allocation exceeded<\/td><\/tr><tr><td>553<\/td><td>Invalid mailbox name or too many recipients<\/td><\/tr><tr><td>554<\/td><td>Transaction failed<\/td><\/tr><tr><td>555<\/td><td>Unsupported protocol version<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Security_and_Policy_Errors_56x%E2%80%9357x\"><\/span>Security and Policy Errors (56x\u201357x)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Code<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td>563<\/td><td>Too many attachments<\/td><\/tr><tr><td>571<\/td><td>Permission or access problem<\/td><\/tr><tr><td>572<\/td><td>Distribution list unavailable<\/td><\/tr><tr><td>573<\/td><td>Internal IP-related error<\/td><\/tr><tr><td>574<\/td><td>Security feature not supported<\/td><\/tr><tr><td>575<\/td><td>Cryptographic error<\/td><\/tr><tr><td>576<\/td><td>Certificate validation issue<\/td><\/tr><tr><td>577<\/td><td>Message integrity error<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Troubleshooting_Tips\"><\/span>Troubleshooting Tips<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Before investigating a specific SMTP error, verify the following:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>The sender&#8217;s email account credentials are correct.<\/li>\n\n\n\n<li>SMTP authentication is enabled.<\/li>\n\n\n\n<li>The domain&#8217;s email service is active.<\/li>\n\n\n\n<li>DNS records (MX, SPF, DKIM, and DMARC) are configured correctly.<\/li>\n\n\n\n<li>The sending server&#8217;s IP address is not listed on email blacklists.<\/li>\n\n\n\n<li>The recipient&#8217;s mailbox exists and has available storage space.<\/li>\n<\/ul>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Summary\"><\/span>Summary<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">SMTP error codes provide valuable information about why an email could not be delivered. Understanding the meaning of the code returned by the mail server can help identify issues related to:<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li>Authentication<\/li>\n\n\n\n<li>Mailbox availability<\/li>\n\n\n\n<li>DNS configuration<\/li>\n\n\n\n<li>Spam filtering<\/li>\n\n\n\n<li>Message size limits<\/li>\n\n\n\n<li>Server connectivity<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\">When troubleshooting delivery failures, always start by examining the complete SMTP error message, as it usually contains more detailed information than the numeric code alone.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n<\/div>","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"template":"","format":"standard","manualknowledgebasecat":[44,45,41],"manual_kb_tag":[242,1435,1452,1468,283,1436,1453,9133,286,1437,1454,562,1438,1455,668,1439,1456,726,1440,1457,772,1441,1458,1088,1443,1459,1423,1444,1460,1428,1445,1461,1429,1446,1462,1430,1447,1463,1431,1448,1464,1432,1449,1465,1433,1450,1466,174,1434,1451,1467],"class_list":["post-869","manual_kb","type-manual_kb","status-publish","format-standard","hentry","manualknowledgebasecat-errors-receiving-messages","manualknowledgebasecat-errors-sending-messages","manualknowledgebasecat-email","manual_kb_tag-mybox","manual_kb_tag-relay-access-denied","manual_kb_tag-delivery-timeout","manual_kb_tag-response-code-meanings","manual_kb_tag-mybox-panel","manual_kb_tag-client-host-rejected","manual_kb_tag-mail-system-full","manual_kb_tag-5-7-1","manual_kb_tag-mail-server","manual_kb_tag-service-unavailable","manual_kb_tag-invalid-mailbox-address","manual_kb_tag-email","manual_kb_tag-smtp-response-codes","manual_kb_tag-syntax-error","manual_kb_tag-domain-settings","manual_kb_tag-email-delivery-failure","manual_kb_tag-command-not-implemented","manual_kb_tag-disk-space","manual_kb_tag-mail-server-errors","manual_kb_tag-authentication-error","manual_kb_tag-domain","manual_kb_tag-bounce-message","manual_kb_tag-unauthorized-delivery","manual_kb_tag-ip-address","manual_kb_tag-mailbox-full","manual_kb_tag-connection-refused","manual_kb_tag-mail-servers","manual_kb_tag-message-too-large","manual_kb_tag-network-interruption","manual_kb_tag-smtp-error-codes","manual_kb_tag-spam-rejection","manual_kb_tag-mail-delivery-issues","manual_kb_tag-email-delivery-errors","manual_kb_tag-blacklist-rejection","manual_kb_tag-error-code-list","manual_kb_tag-mail-server-responses","manual_kb_tag-temporary-failure","manual_kb_tag-mail-error-codes","manual_kb_tag-delivery-status-codes","manual_kb_tag-permanent-failure","manual_kb_tag-smtp-troubleshooting","manual_kb_tag-bounce-messages","manual_kb_tag-address-related-errors","manual_kb_tag-email-server-troubleshooting","manual_kb_tag-recipient-address-rejected","manual_kb_tag-large-message-errors","manual_kb_tag-smtp-status-codes","manual_kb_tag-dns-server","manual_kb_tag-sender-address-rejected","manual_kb_tag-email-bounce","manual_kb_tag-three-digit-codes"],"_links":{"self":[{"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/manual_kb\/869","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/manual_kb"}],"about":[{"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/types\/manual_kb"}],"author":[{"embeddable":true,"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":2,"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/manual_kb\/869\/revisions"}],"predecessor-version":[{"id":4772,"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/manual_kb\/869\/revisions\/4772"}],"wp:attachment":[{"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/media?parent=869"}],"wp:term":[{"taxonomy":"manualknowledgebasecat","embeddable":true,"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/manualknowledgebasecat?post=869"},{"taxonomy":"manual_kb_tag","embeddable":true,"href":"https:\/\/mybox.com\/help\/ro\/wp-json\/wp\/v2\/manual_kb_tag?post=869"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}