1.0Mailrelayhttps://mailrelay.com/en/Mailrelayhttps://mailrelay.com/en/blog/author/mailrelay/rich600338<blockquote class="wp-embedded-content" data-secret="809YRjzwkV"><a href="https://mailrelay.com/en/glossary/greylist/">Greylist</a></blockquote><iframe sandbox="allow-scripts" security="restricted" src="https://mailrelay.com/en/glossary/greylist/embed/#?secret=809YRjzwkV" width="600" height="338" title="“Greylist” — Mailrelay" data-secret="809YRjzwkV" frameborder="0" marginwidth="0" marginheight="0" scrolling="no" class="wp-embedded-content"></iframe><script> /*! This file is auto-generated */ !function(d,l){"use strict";l.querySelector&&d.addEventListener&&"undefined"!=typeof URL&&(d.wp=d.wp||{},d.wp.receiveEmbedMessage||(d.wp.receiveEmbedMessage=function(e){var t=e.data;if((t||t.secret||t.message||t.value)&&!/[^a-zA-Z0-9]/.test(t.secret)){for(var s,r,n,a=l.querySelectorAll('iframe[data-secret="'+t.secret+'"]'),o=l.querySelectorAll('blockquote[data-secret="'+t.secret+'"]'),c=new RegExp("^https?:$","i"),i=0;i<o.length;i++)o[i].style.display="none";for(i=0;i<a.length;i++)s=a[i],e.source===s.contentWindow&&(s.removeAttribute("style"),"height"===t.message?(1e3<(r=parseInt(t.value,10))?r=1e3:~~r<200&&(r=200),s.height=r):"link"===t.message&&(r=new URL(s.getAttribute("src")),n=new URL(t.value),c.test(n.protocol))&&n.host===r.host&&l.activeElement===s&&(d.top.location.href=t.value))}},d.addEventListener("message",d.wp.receiveEmbedMessage,!1),l.addEventListener("DOMContentLoaded",function(){for(var e,t,s=l.querySelectorAll("iframe.wp-embedded-content"),r=0;r<s.length;r++)(t=(e=s[r]).getAttribute("data-secret"))||(t=Math.random().toString(36).substring(2,12),e.src+="#?secret="+t,e.setAttribute("data-secret",t)),e.contentWindow.postMessage({message:"ready",secret:t},"*")},!1)))}(window,document); //# sourceURL=https://mailrelay.com/wp-includes/js/wp-embed.min.js </script> Greylisting (also spelled as graylisting) is a term used in email management, referring to senders that are neither completely blocked (blacklisted) nor completely allowed (whitelisted). This technique helps to decrease the number of spam emails by temporarily delaying emails from unknown senders. Why is greylisting important in email marketing? These lists have several practical uses. […]