{"id":1155,"date":"2025-12-22T09:57:01","date_gmt":"2025-12-22T08:57:01","guid":{"rendered":"https:\/\/mybox.com\/help\/?post_type=manual_kb&#038;p=1155"},"modified":"2026-04-03T09:56:58","modified_gmt":"2026-04-03T07:56:58","slug":"why-didnt-i-receive-a-feedback-message-about-an-undelivered-email","status":"publish","type":"manual_kb","link":"https:\/\/mybox.com\/help\/en\/knowledgebase\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/","title":{"rendered":"Why didn&#8217;t I receive a feedback message about an undelivered email?"},"content":{"rendered":"\n<div class=\"translation-block translation-block-merged\">\n<p class=\"wp-block-paragraph\">Typically, if an email cannot be delivered, the receiving server sends a <strong>Non-Delivery Report (NDR)<\/strong> or &#8220;bounce-back&#8221; message to the sender explaining why.<sup><\/sup> If your recipient did not receive your message and you received no such notification, it usually indicates that the email was &#8220;silently dropped&#8221; or intercepted by a security layer.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">This lack of feedback is a standard defensive measure used by mail servers to prevent spammers from discovering which email addresses are valid.<\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/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\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/#Common_Causes_for_%E2%80%9CSilent%E2%80%9D_Failures\" >Common Causes for &#8220;Silent&#8221; Failures<\/a><ul class='ez-toc-list-level-3' ><li class='ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-2\" href=\"https:\/\/mybox.com\/help\/en\/knowledgebase\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/#1_The_message_was_classified_as_Spam\" >1. The message was classified as Spam<\/a><\/li><li class='ez-toc-page-1 ez-toc-heading-level-3'><a class=\"ez-toc-link ez-toc-heading-3\" href=\"https:\/\/mybox.com\/help\/en\/knowledgebase\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/#2_Silent_Drop_Security_Filtering\" >2. Silent Drop (Security Filtering)<\/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\/en\/knowledgebase\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/#3_Authentication_Failures_SPFDKIM\" >3. Authentication Failures (SPF\/DKIM)<\/a><\/li><\/ul><\/li><li class='ez-toc-page-1 ez-toc-heading-level-2'><a class=\"ez-toc-link ez-toc-heading-5\" href=\"https:\/\/mybox.com\/help\/en\/knowledgebase\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/#Distinction_Block\" >Distinction Block<\/a><\/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\/en\/knowledgebase\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/#Practical_Implications\" >Practical Implications<\/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\/en\/knowledgebase\/why-didnt-i-receive-a-feedback-message-about-an-undelivered-email\/#Summary\" >Summary<\/a><\/li><\/ul><\/nav><\/div>\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Common_Causes_for_%E2%80%9CSilent%E2%80%9D_Failures\"><\/span>Common Causes for &#8220;Silent&#8221; Failures<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"1_The_message_was_classified_as_Spam\"><\/span>1. The message was classified as Spam<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<\/div>\n\n<div id=\"mybox-1253444806\" 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 frequent reason for a missing notification is that the recipient&#8217;s server accepted the message but immediately flagged it as spam.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>The result:<\/strong> The email is placed in the recipient\u2019s <strong>Junk\/Spam folder<\/strong> rather than being rejected. Since the message was &#8220;delivered&#8221; (just not to the Inbox), no bounce-back is generated.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"2_Silent_Drop_Security_Filtering\"><\/span>2. Silent Drop (Security Filtering)<span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">If a receiving server&#8217;s filters determine that a message is highly malicious (containing known viruses or links to phishing sites), it may perform a <strong>Silent Drop<\/strong>.<\/p>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>The result:<\/strong> The server deletes the message entirely without notifying the sender or the recipient. This prevents the sender from knowing they have hit a &#8220;live&#8221; target or triggered a specific filter.<\/li>\n<\/ul>\n\n\n\n<h3 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"3_Authentication_Failures_SPFDKIM\"><\/span>3. Authentication Failures (SPF\/DKIM)<sup><\/sup><span class=\"ez-toc-section-end\"><\/span><\/h3>\n\n\n\n<p class=\"wp-block-paragraph\" id=\"p-rc_43b2e33574b2e9f3-30\">If your domain\u2019s security records (SPF or DKIM) are missing or incorrectly configured, some providers (like Gmail or Outlook) may reject your mail without sending a formal error message to protect their users.<sup><\/sup><\/p>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Distinction_Block\"><\/span>Distinction Block<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\">\n<p class=\"wp-block-paragraph\" id=\"p-rc_43b2e33574b2e9f3-31\"><strong>Bounce-back vs. Silent Drop<\/strong> A <strong>Bounce-back<\/strong> happens when a server explicitly rejects a message (e.g., &#8220;Mailbox full&#8221;).<sup><\/sup> A <strong>Silent Drop<\/strong> happens when a server accepts the message but decides it is too high-risk to place in any folder, providing no feedback to the sender.<\/p>\n<\/blockquote>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\n\n\n\n<h2 class=\"wp-block-heading\"><span class=\"ez-toc-section\" id=\"Practical_Implications\"><\/span>Practical Implications<span class=\"ez-toc-section-end\"><\/span><\/h2>\n\n\n\n<ul class=\"wp-block-list\">\n<li><strong>Check the Spam Folder:<\/strong> Always ask the recipient to check their Spam or Junk folder first. If the message is there, it means your content or sender reputation triggered a filter, but the delivery technically succeeded.<\/li>\n\n\n\n<li><strong>Verify your Records:<\/strong> Ensure your <strong>mybox<\/strong> account has active SPF and DKIM records. This proves your identity to external servers and reduces the chance of being &#8220;silently dropped.&#8221;<\/li>\n\n\n\n<li><strong>Contact Recipient Support:<\/strong> If the email is not in the Spam folder, the recipient&#8217;s IT support is the only party capable of checking their server logs to see why the message was discarded.<\/li>\n\n\n\n<li><strong>Wait 24 Hours:<\/strong> Occasionally, a &#8220;soft&#8221; failure occurs where the server is still retrying the delivery. You may only receive an undelivered notification after the retry period expires (usually 24\u201372 hours).<\/li>\n<\/ul>\n\n\n\n<p class=\"wp-block-paragraph\"><\/p>\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\">The absence of a feedback message usually means the receiving server accepted the email but categorized it as a security risk or spam. To resolve this, verify your email authentication settings and coordinate with the recipient to white-list your address.<\/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":[321,335,336,337,338,339,340,341,342,343],"class_list":["post-1155","manual_kb","type-manual_kb","status-publish","format-standard","hentry","manualknowledgebasecat-email","manualknowledgebasecat-errors-sending-messages","manual_kb_tag-email-troubleshooting","manual_kb_tag-undelivered-email","manual_kb_tag-email-not-delivered","manual_kb_tag-delivery-failure","manual_kb_tag-bounce-notification","manual_kb_tag-email-deliverability","manual_kb_tag-spam-filters","manual_kb_tag-spam-folder","manual_kb_tag-message-not-delivered","manual_kb_tag-undelivered-message"],"_links":{"self":[{"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb\/1155","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\/1155\/revisions"}],"predecessor-version":[{"id":7460,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb\/1155\/revisions\/7460"}],"wp:attachment":[{"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/media?parent=1155"}],"wp:term":[{"taxonomy":"manualknowledgebasecat","embeddable":true,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manualknowledgebasecat?post=1155"},{"taxonomy":"manual_kb_tag","embeddable":true,"href":"https:\/\/mybox.com\/help\/en\/wp-json\/wp\/v2\/manual_kb_tag?post=1155"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}