{"id":803,"date":"2025-12-19T09:49:31","date_gmt":"2025-12-19T08:49:31","guid":{"rendered":"https:\/\/mybox.com\/help\/?post_type=manual_kb&#038;p=803"},"modified":"2026-02-06T12:45:31","modified_gmt":"2026-02-06T11:45:31","slug":"possible-reasons-for-message-failure","status":"publish","type":"manual_kb","link":"https:\/\/mybox.com\/help\/en\/knowledgebase\/possible-reasons-for-message-failure\/","title":{"rendered":"Possible reasons for message failure"},"content":{"rendered":"\n<div class=\"translation-block translation-block-merged\">\n<p class=\"wp-block-paragraph\">In many cases, if your message cannot be delivered to the recipient, you will receive an automatic return email, which will include, among other things, the reason for the non-delivery.<\/p>\n\n\n\n<\/div>\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"731\" height=\"204\" src=\"https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-330.png\" alt=\"\" class=\"wp-image-4767\" srcset=\"https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-330.png 731w, https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-330-300x84.png 300w, https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-330-18x5.png 18w\" sizes=\"auto, (max-width: 731px) 100vw, 731px\" \/><\/figure>\n\n<div class=\"translation-block translation-block-merged\">\n\n\n\n<p class=\"wp-block-paragraph\">Below you will find the most common mistakes in delivering emails to recipients.<\/p>\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\/en\/knowledgebase\/possible-reasons-for-message-failure\/#Account_issues\" >Account issues<\/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\/en\/knowledgebase\/possible-reasons-for-message-failure\/#Exceeded_Mailbox_Quota\" >Exceeded Mailbox Quota<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/mybox.com\/help\/en\/knowledgebase\/possible-reasons-for-message-failure\/#Connection_Time_Exceeded\" >Connection Time Exceeded<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-4\" href=\"https:\/\/mybox.com\/help\/en\/knowledgebase\/possible-reasons-for-message-failure\/#Sender_Verification_Error\" >Sender Verification Error<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Account_issues\"><\/span>Account issues<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<\/div>\n\n<div id=\"mybox-2923110647\" 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\">Early access<\/span><\/span>\r\n      <h4><span class=\"translation-block translation-block-banner-text\">Still need help?<\/span><\/h4>\r\n      <p><span class=\"translation-block translation-block-banner-text\">Contact our customer service team.<\/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\">Message us<\/span><\/a>\r\n  <\/div>\r\n<\/div><\/div>\n\n<div class=\"translation-block translation-block-merged\"><p class=\"wp-block-paragraph\">The most common reason for errors marked as <strong>&#8220;Recipent address rejected&#8221;<\/strong> is an incorrectly entered recipient address. Perhaps a typo crept in when typing it or the box to which you want to send your message simply does not exist.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Exceeded_Mailbox_Quota\"><\/span>Exceeded Mailbox Quota<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<\/div>\n\n<figure class=\"wp-block-image size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"598\" height=\"278\" src=\"https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-331.png\" alt=\"\" class=\"wp-image-4769\" srcset=\"https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-331.png 598w, https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-331-300x139.png 300w, https:\/\/mybox.com\/help\/wp-content\/uploads\/2025\/12\/image-331-18x8.png 18w\" sizes=\"auto, (max-width: 598px) 100vw, 598px\" \/><\/figure>\n\n<div class=\"translation-block translation-block-merged\">\n\n\n\n<p class=\"wp-block-paragraph\">When <strong>&#8220;Mailbox is over quota&#8221;<\/strong> appears in the return email after sending a message, it means that the recipient&#8217;s inbox is overfilled and cannot accept your email.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Connection_Time_Exceeded\"><\/span>Connection Time Exceeded<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">If you find <strong>the phrase &#8220;Connection timed out&#8221;<\/strong> in the return message, it means that our servers were unable to connect to the recipient&#8217;s infrastructure. In this case, we will try to deliver the message a few more times. Perhaps at some point the message will be delivered.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">If after several attempts the shipment still does not take place, you will receive a notification of failure. In this case, be sure to contact the Customer Service Office via the Helpdesk 24h or by phone.<\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Sender_Verification_Error\"><\/span>Sender Verification Error<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">When you see <strong>the message &#8220;5.7.8 Error: authentication failed: authentication failure&#8221;<\/strong> after sending the message, it probably means that you have saved the wrong login details for mybox.com mail servers in your email client. Verify that the mailbox password you entered is correct.<\/p>\n<\/div>\n","protected":false},"author":1,"featured_media":0,"parent":0,"menu_order":0,"template":"","format":"standard","manualknowledgebasecat":[41,45],"manual_kb_tag":[226,1952,1975,242,1960,1976,562,1961,1977,978,1962,1978,1014,1963,1979,1288,1964,1980,1396,1965,1981,1423,1966,1982,1433,1967,1439,1968,1441,1969,1461,1970,1518,1971,1784,1972,207,1801,1973,216,1805,1974],"class_list":["post-803","manual_kb","type-manual_kb","status-publish","format-standard","hentry","manualknowledgebasecat-email","manualknowledgebasecat-errors-sending-messages","manual_kb_tag-customer-service","manual_kb_tag-mailbox-quota","manual_kb_tag-wrong-login-details","manual_kb_tag-mybox","manual_kb_tag-bounce-back","manual_kb_tag-email-client-settings","manual_kb_tag-email","manual_kb_tag-non-delivery-report","manual_kb_tag-helpdesk-2h","manual_kb_tag-helpdesk","manual_kb_tag-return-email","manual_kb_tag-full-inbox","manual_kb_tag-mybox-com","manual_kb_tag-incorrect-recipient-address","manual_kb_tag-mail-delivery-errors","manual_kb_tag-sender-verification","manual_kb_tag-mailbox-over-quota","manual_kb_tag-email-bounce-reasons","manual_kb_tag-mail-server-settings","manual_kb_tag-undeliverable-email","manual_kb_tag-smtp-authentication-error","manual_kb_tag-mail-servers","manual_kb_tag-non-delivery-notification","manual_kb_tag-delivery-status-notification","manual_kb_tag-recipient-address-rejected","manual_kb_tag-delivery-failure-notice","manual_kb_tag-email-delivery-failure","manual_kb_tag-typo-in-email-address","manual_kb_tag-bounce-message","manual_kb_tag-exceeded-mailbox-quota","manual_kb_tag-mail-delivery-issues","manual_kb_tag-connection-timed-out","manual_kb_tag-find","manual_kb_tag-connection-time-exceeded","manual_kb_tag-email-client","manual_kb_tag-failed-delivery-attempts","manual_kb_tag-phone","manual_kb_tag-email-delivery","manual_kb_tag-sender-verification-error","manual_kb_tag-login-details","manual_kb_tag-recipient-address","manual_kb_tag-authentication-failed"],"_links":{"self":[{"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb\/803","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb"}],"about":[{"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/types\/manual_kb"}],"author":[{"embeddable":true,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/users\/1"}],"version-history":[{"count":1,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb\/803\/revisions"}],"predecessor-version":[{"id":4770,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb\/803\/revisions\/4770"}],"wp:attachment":[{"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/media?parent=803"}],"wp:term":[{"taxonomy":"manualknowledgebasecat","embeddable":true,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manualknowledgebasecat?post=803"},{"taxonomy":"manual_kb_tag","embeddable":true,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb_tag?post=803"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}