CINXE.COM
Postmark email deliverability glossary
<!doctype html> <html lang="en" class="no-js"> <head> <meta charset="utf-8"> <meta http-equiv="X-UA-Compatible" content="IE=edge"> <title> Postmark email deliverability glossary </title> <meta name="description" content="Everything you need to know to send great email."> <meta name="viewport" content="width=device-width, initial-scale=1"> <meta name="globalsign-domain-verification" content="F0n5fUwYguswb99EGyC5qD87O15uv5VBUiX9yRrxX6"> <meta name="theme-color" content="#FFDE00"> <script>dataLayer = [{'siteType': 'landing', 'visitorIP': '8.222.208.146', 'doNotTrack': 0 }];</script> <link href="https://postmarkapp.com/dist/css/core.233bca689f85085cd63f.css" rel="stylesheet"> <link href="https://postmarkapp.com/dist/css/postmark.a8d5a5af7491033cd10b.css" rel="stylesheet"> <link rel="dns-prefetch" href="https://ssl.google-analytics.com"> <link rel="dns-prefetch" href="https://www.google-analytics.com"> <link rel="shortcut icon" href="/images/favicon.ico"> <link rel="apple-touch-icon" href="/images/apple-touch-icon.png"> <link rel="canonical" href="https://postmarkapp.com/glossary"> <meta property="og:url" content="https://postmarkapp.com/glossary"> <meta property="og:type" content="website"> <meta property="fb:app_id" content="244883355940334"> <meta property="og:title" content="Postmark email deliverability glossary"> <meta property="og:description" content="Everything you need to know to send great email."> <meta property="og:image" content="https://postmarkapp.com/images/logo-stamp-social.png"> <meta name="twitter:title" content="Postmark email deliverability glossary"> <meta name="twitter:description" content="Everything you need to know to send great email."> <meta name="twitter:card" content="summary"> <meta name="twitter:image" content="https://postmarkapp.com/images/logo-stamp-social.png"> <meta name="twitter:site" content="@postmarkapp"> <meta name="slack-app-id" content="A8LSJN934"> <link rel="alternate" href="https://postmarkapp.com/glossary/feed.atom" type="application/atom+xml" title="Postmark Glossary"> </head> <body> <div class="alert alert--info alert--centered" id="alert-346478"> <div class="u-container alert_container"> <div class="alert_message"> <strong>Grow with us: Join Postmark's new referral partner program and start earning</strong> </div> <div class="alert_actions"> <a href="https://postmarkapp.com/lp/referral-partner-program" target="_blank" class="cta-btn cta-btn--inverted">Learn more</a> </div> </div> <a href="#" class="alert_dismiss" data-id="346478">x</a> </div> <header class="header "> <div class="u-container header_container"> <div class="header_branding"> <a href="https://postmarkapp.com/" class="header_postmark-logo">Postmark</a> <div class="header_actions"> <a href="https://account.postmarkapp.com/login" class="header_login cta-btn cta-btn--small ">Log In</a> <button class="header_hamburger js-nav-mobile-button" aria-haspopup="true"> <span></span> <span></span> <span></span> </button> </div> </div> <nav class="nav nav--header nav--desktop" role="navigation" aria-label="Main"> <ul class="nav_list"> <li class="nav_item "> <a href="https://postmarkapp.com/why" class="nav_link">Why Postmark?</a> </li> <li class="nav_item nav_item--dropdown"> <button class="nav_link js-nav-popup" aria-haspopup="true" aria-expanded="false" data-target=".js-dropdown-product">Product</button> <div class="nav_dropdown js-dropdown-product"> <div class="nav_dropdown-wrapper nav_dropdown-wrapper--product"> <div class="nav_features"> <h2 class="nav_sub-heading nav_sub-heading--features">Features</h2> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/email-api" class="nav_link"> <span class="nav_icon nav_icon--email-api"></span> <span class="nav_title">Email API</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/smtp-service" class="nav_link"> <span class="nav_icon nav_icon--smtp"></span> <span class="nav_title">SMTP Service</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/message-streams" class="nav_link"> <span class="nav_icon nav_icon--streams"></span> <span class="nav_title">Message Streams</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/transactional-email" class="nav_link"> <span class="nav_icon nav_icon--transactional"></span> <span class="nav_title">Transactional Email</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-delivery" class="nav_link"> <span class="nav_icon nav_icon--delivery"></span> <span class="nav_title">Email Delivery</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-templates" class="nav_link"> <span class="nav_icon nav_icon--templates"></span> <span class="nav_title">Email Templates</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/inbound-email" class="nav_link"> <span class="nav_icon nav_icon--inbound"></span> <span class="nav_title">Inbound Email</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-analytics" class="nav_link"> <span class="nav_icon nav_icon--insight"></span> <span class="nav_title">Analytics & Retention</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/integrations" class="nav_link"> <span class="nav_icon nav_icon--integrations"></span> <span class="nav_title">Integrations</span> </a> </li> </ul> </div> <div class="nav_sub"> <h2 class="nav_sub-heading"> <span class="nav_icon nav_icon--for"></span> <span class="nav_text">Postmark For</span> </h2> <ul class="nav_list"> <li><a href="https://postmarkapp.com/for/agencies" class="nav_sub-link">Agencies</a></li> <li><a href="https://postmarkapp.com/for/enterprise" class="nav_sub-link">Enterprise</a></li> <li><a href="https://postmarkapp.com/for/startups" class="nav_sub-link">Startups</a></li> <li><a href="https://postmarkapp.com/for/bootstrapped-startups" class="nav_sub-link">Bootstrapped Startups</a></li> <li><a href="https://postmarkapp.com/for/side-projects" class="nav_sub-link">Side Projects</a></li> </ul> <h2 class="nav_sub-heading u-pad-top--xs"> <span class="nav_icon nav_icon--versus"></span> <span class="nav_text">Postmark vs.</span> </h2> <ul class="nav_list"> <li><a href="https://postmarkapp.com/compare/sendgrid-alternative" class="nav_sub-link">SendGrid</a></li> <li><a href="https://postmarkapp.com/compare/mailgun-alternative" class="nav_sub-link">Mailgun</a></li> <li><a href="https://postmarkapp.com/compare/amazon-ses-alternative" class="nav_sub-link">Amazon SES</a></li> <li><a href="https://postmarkapp.com/compare/sparkpost-alternative" class="nav_sub-link">SparkPost</a></li> <li><a href="https://postmarkapp.com/compare/mandrill-alternative" class="nav_sub-link">Mandrill</a></li> </ul> </div> </div> </div> </li> <li class="nav_item"> <a href="https://postmarkapp.com/pricing" class="nav_link">Pricing</a> </li> <li class="nav_item nav_item--dropdown nav_item--current"> <button class="nav_link js-nav-popup" aria-haspopup="true" aria-expanded="false" data-target=".js-dropdown-resources">Resources</button> <div class="nav_dropdown js-dropdown-resources"> <div class="nav_dropdown-wrapper"> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/blog" class="nav_link"> <span class="nav_icon nav_icon--blog"></span> <span class="nav_title">Blog</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/developer" class="nav_link"> <span class="nav_icon nav_icon--api-docs"></span> <span class="nav_title">API Documentation</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/manual" class="nav_link"> <span class="nav_icon nav_icon--manual"></span> <span class="nav_title">Getting Started</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/guides" class="nav_link"> <span class="nav_icon nav_icon--guides"></span> <span class="nav_title">Email Guides</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/postmark-express" class="nav_link"> <span class="nav_icon nav_icon--comic"></span> <span class="nav_title">Email Comic</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/webinars" class="nav_link"> <span class="nav_icon nav_icon--webinars"></span> <span class="nav_title">Webinars</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/videos" class="nav_link"> <span class="nav_icon nav_icon--videos"></span> <span class="nav_title">Videos</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/podcast" class="nav_link"> <span class="nav_icon nav_icon--podcast"></span> <span class="nav_title">Podcast</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/labs" class="nav_link"> <span class="nav_icon nav_icon--labs"></span> <span class="nav_title">Labs</span> </a> </li> <li class="nav_item"> <a href="https://dmarcdigests.com" target="_blank" rel="noopener" class="nav_link"> <span class="nav_icon nav_icon--dmarc"></span> <span class="nav_title">DMARC Digests</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/glossary" class="nav_link"> <span class="nav_icon nav_icon--glossary"></span> <span class="nav_title">Glossary</span> </a> </li> </ul> </div> </div> </li> <li class="nav_item nav_item--dropdown"> <button class="nav_link js-nav-popup" aria-haspopup="true" aria-expanded="false" data-target=".js-dropdown-help">Help</button> <div class="nav_dropdown js-dropdown-help"> <div class="nav_dropdown-wrapper"> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/support" class="nav_link"> <span class="nav_icon nav_icon--support"></span> <span class="nav_title">Support Center</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/contact" class="nav_link"> <span class="nav_icon nav_icon--contact"></span> <span class="nav_title">Contact Support</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/talk-to-sales" class="nav_link"> <span class="nav_icon nav_icon--contact-sales"></span> <span class="nav_title">Talk to Sales</span> </a> </li> <li class="nav_item"> <a href="https://status.postmarkapp.com/" target="_blank" rel="noopener noreferrer" class="nav_link"> <span class="nav_icon nav_icon--status"></span> <span class="nav_title">Status</span> </a> </li> </ul> </div> </div> </li> <li class="nav_item nav_item--btn"> <a href="https://account.postmarkapp.com/login" class="nav_btn cta-btn ">Log in</a> </li> <li class="nav_item nav_item--btn"> <a href="https://account.postmarkapp.com/sign_up" class="nav_btn cta-btn cta-btn--default js-signup" data-track="Click" data-category="Signup Button" data-label="Header">Start free trial</a> </li> </ul> </nav> <div class="nav-mobile js-nav-mobile hidden--at-l-2"> <img src="/images/logo-stamp-simple.svg" class="nav-mobile_logo" /> <nav class="nav nav--header nav--mobile" role="navigation" aria-label="Main"> <ul class="nav_list"> <li class="nav_item "> <a href="https://postmarkapp.com/why" class="nav_link">Why Postmark?</a> </li> <li class="nav_item nav_item--dropdown"> <button class="nav_link js-nav-popup" aria-haspopup="true" aria-expanded="false" data-target=".js-dropdown-product">Product</button> <div class="nav_dropdown js-dropdown-product"> <div class="nav_dropdown-wrapper nav_dropdown-wrapper--product"> <div class="nav_features"> <h2 class="nav_sub-heading nav_sub-heading--features">Features</h2> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/email-api" class="nav_link"> <span class="nav_icon nav_icon--email-api"></span> <span class="nav_title">Email API</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/smtp-service" class="nav_link"> <span class="nav_icon nav_icon--smtp"></span> <span class="nav_title">SMTP Service</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/message-streams" class="nav_link"> <span class="nav_icon nav_icon--streams"></span> <span class="nav_title">Message Streams</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/transactional-email" class="nav_link"> <span class="nav_icon nav_icon--transactional"></span> <span class="nav_title">Transactional Email</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-delivery" class="nav_link"> <span class="nav_icon nav_icon--delivery"></span> <span class="nav_title">Email Delivery</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-templates" class="nav_link"> <span class="nav_icon nav_icon--templates"></span> <span class="nav_title">Email Templates</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/inbound-email" class="nav_link"> <span class="nav_icon nav_icon--inbound"></span> <span class="nav_title">Inbound Email</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-analytics" class="nav_link"> <span class="nav_icon nav_icon--insight"></span> <span class="nav_title">Analytics & Retention</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/integrations" class="nav_link"> <span class="nav_icon nav_icon--integrations"></span> <span class="nav_title">Integrations</span> </a> </li> </ul> </div> <div class="nav_sub"> <h2 class="nav_sub-heading"> <span class="nav_icon nav_icon--for"></span> <span class="nav_text">Postmark For</span> </h2> <ul class="nav_list"> <li><a href="https://postmarkapp.com/for/agencies" class="nav_sub-link">Agencies</a></li> <li><a href="https://postmarkapp.com/for/enterprise" class="nav_sub-link">Enterprise</a></li> <li><a href="https://postmarkapp.com/for/startups" class="nav_sub-link">Startups</a></li> <li><a href="https://postmarkapp.com/for/bootstrapped-startups" class="nav_sub-link">Bootstrapped Startups</a></li> <li><a href="https://postmarkapp.com/for/side-projects" class="nav_sub-link">Side Projects</a></li> </ul> <h2 class="nav_sub-heading u-pad-top--xs"> <span class="nav_icon nav_icon--versus"></span> <span class="nav_text">Postmark vs.</span> </h2> <ul class="nav_list"> <li><a href="https://postmarkapp.com/compare/sendgrid-alternative" class="nav_sub-link">SendGrid</a></li> <li><a href="https://postmarkapp.com/compare/mailgun-alternative" class="nav_sub-link">Mailgun</a></li> <li><a href="https://postmarkapp.com/compare/amazon-ses-alternative" class="nav_sub-link">Amazon SES</a></li> <li><a href="https://postmarkapp.com/compare/sparkpost-alternative" class="nav_sub-link">SparkPost</a></li> <li><a href="https://postmarkapp.com/compare/mandrill-alternative" class="nav_sub-link">Mandrill</a></li> </ul> </div> </div> </div> </li> <li class="nav_item"> <a href="https://postmarkapp.com/pricing" class="nav_link">Pricing</a> </li> <li class="nav_item nav_item--dropdown nav_item--current"> <button class="nav_link js-nav-popup" aria-haspopup="true" aria-expanded="false" data-target=".js-dropdown-resources">Resources</button> <div class="nav_dropdown js-dropdown-resources"> <div class="nav_dropdown-wrapper"> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/blog" class="nav_link"> <span class="nav_icon nav_icon--blog"></span> <span class="nav_title">Blog</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/developer" class="nav_link"> <span class="nav_icon nav_icon--api-docs"></span> <span class="nav_title">API Documentation</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/manual" class="nav_link"> <span class="nav_icon nav_icon--manual"></span> <span class="nav_title">Getting Started</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/guides" class="nav_link"> <span class="nav_icon nav_icon--guides"></span> <span class="nav_title">Email Guides</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/postmark-express" class="nav_link"> <span class="nav_icon nav_icon--comic"></span> <span class="nav_title">Email Comic</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/webinars" class="nav_link"> <span class="nav_icon nav_icon--webinars"></span> <span class="nav_title">Webinars</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/videos" class="nav_link"> <span class="nav_icon nav_icon--videos"></span> <span class="nav_title">Videos</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/podcast" class="nav_link"> <span class="nav_icon nav_icon--podcast"></span> <span class="nav_title">Podcast</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/labs" class="nav_link"> <span class="nav_icon nav_icon--labs"></span> <span class="nav_title">Labs</span> </a> </li> <li class="nav_item"> <a href="https://dmarcdigests.com" target="_blank" rel="noopener" class="nav_link"> <span class="nav_icon nav_icon--dmarc"></span> <span class="nav_title">DMARC Digests</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/glossary" class="nav_link"> <span class="nav_icon nav_icon--glossary"></span> <span class="nav_title">Glossary</span> </a> </li> </ul> </div> </div> </li> <li class="nav_item nav_item--dropdown"> <button class="nav_link js-nav-popup" aria-haspopup="true" aria-expanded="false" data-target=".js-dropdown-help">Help</button> <div class="nav_dropdown js-dropdown-help"> <div class="nav_dropdown-wrapper"> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/support" class="nav_link"> <span class="nav_icon nav_icon--support"></span> <span class="nav_title">Support Center</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/contact" class="nav_link"> <span class="nav_icon nav_icon--contact"></span> <span class="nav_title">Contact Support</span> </a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/talk-to-sales" class="nav_link"> <span class="nav_icon nav_icon--contact-sales"></span> <span class="nav_title">Talk to Sales</span> </a> </li> <li class="nav_item"> <a href="https://status.postmarkapp.com/" target="_blank" rel="noopener noreferrer" class="nav_link"> <span class="nav_icon nav_icon--status"></span> <span class="nav_title">Status</span> </a> </li> </ul> </div> </div> </li> <li class="nav_item nav_item--btn"> <a href="https://account.postmarkapp.com/login" class="nav_btn cta-btn ">Log in</a> </li> <li class="nav_item nav_item--btn"> <a href="https://account.postmarkapp.com/sign_up" class="nav_btn cta-btn cta-btn--default js-signup" data-track="Click" data-category="Signup Button" data-label="Header">Start free trial</a> </li> </ul> </nav> <div class="nav-mobile_extras"> <a href="https://account.postmarkapp.com/sign_up" class="cta-btn cta-btn--default cta-btn--medium js-signup" data-track="Click" data-category="Signup Button" data-label="Header (Mobile)">Start free trial</a> <p class="nav-mobile_login">Already have an account? <a href="https://account.postmarkapp.com/login">Log in →</a></p> </div> </div> </div> </header> <div class="page u-clearfix"> <header class="hero hero--header"> <div class="u-container"> <h1 class="hero_title title-hero">Email deliverability glossary</h1> <p class="hero_desc">Everything you need to know to send great email.</p> <img src="/images/hero/glossary-header.svg" class="guide-head_image" style="max-width: 352.5px; max-height: 110px;"> </div> </header> <div class="tiles"> <ul class="tiles_items"> <li class="tiles_item "> <a href="https://postmarkapp.com/glossary/dkim-domainkeys-identified-mail" class="tile tile--guide " > <div class="tile_body"> <h2 class="tile_title "> DKIM (DomainKeys Identified Mail), explained </h2> <p class="tile_desc">An email authentication method that uses public-key cryptography to verify that emails were not altered in transit.</p> </div> </a> </li> <li class="tiles_item "> <a href="https://postmarkapp.com/glossary/dmarc" class="tile tile--guide " > <div class="tile_body"> <h2 class="tile_title "> DMARC (Domain-based Message Authentication, Reporting & Conformance), explained </h2> <p class="tile_desc">An email security standard that protects against spoofing and phishing.</p> </div> </a> </li> <li class="tiles_item "> <a href="https://postmarkapp.com/glossary/domain-reputation" class="tile tile--guide " > <div class="tile_body"> <h2 class="tile_title "> Domain reputation, explained </h2> <p class="tile_desc">Domain reputation is the opinion receivers have of your domain, which helps them decide if your emails make it to the inbox.</p> </div> </a> </li> <li class="tiles_item "> <a href="https://postmarkapp.com/glossary/email-authentication" class="tile tile--guide " > <div class="tile_body"> <h2 class="tile_title "> Email authentication, explained </h2> <p class="tile_desc">Email authentication is the process used by receiving mail servers to verify the legitimacy of an email message.</p> </div> </a> </li> <li class="tiles_item "> <a href="https://postmarkapp.com/glossary/ip-reputation" class="tile tile--guide " > <div class="tile_body"> <h2 class="tile_title "> IP reputation, explained </h2> <p class="tile_desc">IP reputation is the level of trust inbox providers place on your sending IP (Internet Protocol) address.</p> </div> </a> </li> <li class="tiles_item "> <a href="https://postmarkapp.com/glossary/sender-policy-framework" class="tile tile--guide " > <div class="tile_body"> <h2 class="tile_title "> SPF (Sender Policy Framework), explained </h2> <p class="tile_desc">An email authentication standard that helps detect forged sender addresses.</p> </div> </a> </li> <li class="tiles_item "> <a href="https://postmarkapp.com/glossary/email-deliverability" class="tile tile--guide " > <div class="tile_body"> <h2 class="tile_title "> What is email deliverability? </h2> <p class="tile_desc">Email deliverability is the ability to deliver an email to a recipient’s inbox in a timely manner.</p> </div> </a> </li> </ul> </div> </div> <footer class="footer "> <div class="u-container footer_container"> <nav class="nav nav--footer " role="navigation" aria-label="Footer"> <div class="nav_group"> <h4 class="nav_heading">Product</h4> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/pricing" class="nav_link">Pricing</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/customers" class="nav_link">Customers</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/reviews" class="nav_link">Reviews</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/dedicated-ips" class="nav_link">Dedicated IPs</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/ios" class="nav_link">iOS App</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/lp/referral-partner-program" class="nav_link">Referral Partner Program</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/updates" class="nav_link nav_link--updates" data-latest-update="1731514860">Latest Updates</a> </li> </ul> </div> <div class="nav_group"> <h4 class="nav_heading">Features</h4> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/email-api" class="nav_link">Email API</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/smtp-service" class="nav_link">SMTP Service</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/message-streams" class="nav_link">Message Streams</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/transactional-email" class="nav_link">Transactional Email</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-delivery" class="nav_link">Email Delivery</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-templates" class="nav_link">Templates</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/inbound-email" class="nav_link">Inbound Email</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-analytics" class="nav_link">Analytics & Retention</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/integrations" class="nav_link">Integrations</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-webhooks" class="nav_link">Webhooks</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/security" class="nav_link">Security</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/email-experts" class="nav_link">Email Experts</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/rebound" class="nav_link">Rebound</a> </li> </ul> </div> <div class="nav_group"> <h4 class="nav_heading">Postmark For</h4> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/for/agencies" class="nav_link">Agencies</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/for/startups" class="nav_link">Startups</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/for/enterprise" class="nav_link">Enterprise</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/for/bootstrapped-startups" class="nav_link">Bootstrapped Startups</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/for/side-projects" class="nav_link">Side Projects</a> </li> <li class="nav_item"> <a href="/send-email" class="nav_link">Developers</a> </li> </ul> <h4 class="nav_heading">Postmark vs.</h4> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/compare/sendgrid-alternative" title="Compare Postmark to SendGrid" class="nav_link">SendGrid</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/compare/sparkpost-alternative" title="Compare Postmark to SparkPost" class="nav_link">SparkPost</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/compare/mailgun-alternative" title="Compare Postmark to Mailgun" class="nav_link">Mailgun</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/compare/amazon-ses-alternative" title="Compare Postmark to Amazon SES" class="nav_link">Amazon SES</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/compare/mandrill-alternative" title="Compare Postmark to Mandrill" class="nav_link">Mandrill</a> </li> </ul> </div> <div class="nav_group"> <h4 class="nav_heading">Resources</h4> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/blog" class="nav_link">Blog</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/developer" class="nav_link">API Documentation</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/manual" class="nav_link">Getting Started</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/guides" class="nav_link">Email Guides</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/postmark-express" class="nav_link">Email Comic</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/videos" class="nav_link">Videos</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/podcast" class="nav_link">Podcast</a> </li> <li class="nav_item"> <a href="https://dmarcdigests.com" target="_blank" rel="noopener" class="nav_link">DMARC Digests</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/webinars" class="nav_link">Webinars</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/labs" class="nav_link">Labs</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/migration-guides" class="nav_link">Migration Guides</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/newsletter" class="nav_link">Newsletter</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/glossary" class="nav_link">Glossary</a> </li> </ul> </div> <div class="nav_group"> <h4 class="nav_heading">Help</h4> <ul class="nav_list"> <li class="nav_item"> <a href="https://postmarkapp.com/support" class="nav_link">Support Center</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/contact" class="nav_link">Contact Support</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/talk-to-sales" class="nav_link">Talk to Sales</a> </li> <li class="nav_item"> <a href="https://status.postmarkapp.com" target="_blank" rel="noopener noreferrer" class="nav_link">Service Status</a> </li> </ul> <h4 class="nav_heading">Visit ActiveCampaign for:</h4> <ul class="nav_list"> <li class="nav_item"> <a href="https://www.activecampaign.com/marketing-automation?utm_source=postmark&utm_medium=referral&utm_campaign=postmark_web&utm_content=postmark_footer_nav" target="_blank" rel="noopener" class="nav_link">Marketing Automation</a> </li> <li class="nav_item"> <a href="https://www.activecampaign.com/sales-crm?utm_source=postmark&utm_medium=referral&utm_campaign=postmark_web&utm_content=postmark_footer_nav" target="_blank" rel="noopener" class="nav_link">CRM & Sales Automation</a> </li> <li class="nav_item"> <a href="https://www.activecampaign.com/omnichannel/landing-pages?utm_source=postmark&utm_medium=referral&utm_campaign=postmark_web&utm_content=postmark_footer_nav" target="_blank" rel="noopener" class="nav_link">Landing Pages</a> </li> <li class="nav_item"> <a href="https://www.activecampaign.com/omnichannel/sms-marketing?utm_source=postmark&utm_medium=referral&utm_campaign=postmark_web&utm_content=postmark_footer_nav" target="_blank" rel="noopener" class="nav_link">SMS Automation</a> </li> </ul> </div> </nav> <div class="u-grid u-grid--full u-grid--1of3-at-large footer_lower"> <div class="u-grid-cell"> <div class="footer_ac"> Made with <span class="footer_love">♥</span> at <a href="https://www.activecampaign.com?utm_source=postmark&utm_medium=referral&utm_campaign=postmark_web&utm_content=postmark_footer" class="footer_ac-logo" target="_blank" rel="noopener">ActiveCampaign</a></a> </div> </div> <div class="u-grid-cell u-grid-cell--2of3"> <div class="nav nav--legal"> <ul class="nav_list nav_list--legal"> <li class="nav_item"> <a href="https://postmarkapp.com/privacy-policy" class="nav_link">Privacy Policy</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/cookie-policy" class="nav_link">Cookie Policy</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/terms-of-service" class="nav_link">Terms of Service</a> </li> <li class="nav_item"> <a href="https://postmarkapp.com/eu-privacy" class="nav_link">EU Data Protection</a> </li> <li class="nav_item">© ActiveCampaign, <abbr>LLC</abbr>, 2025.</li> </ul> </div> </div> </div> </div> </footer> <button class="fake-hs-beacon hidden js-load-beacon"> <span class="fake-hs-beacon_icon"></span> <span class="fake-hs-beacon_text">Help</span> </button> <script src="https://postmarkapp.com/dist/js/landing.9aabe3a6f1bb65b85588.js"></script> <script type="text/javascript"> window['GoogleAnalyticsObject'] = 'ga'; window['ga'] = window['ga'] || function() { (window['ga'].q = window['ga'].q || []).push(arguments) }; </script> <!-- Google Tag Manager --> <noscript><iframe src="//www.googletagmanager.com/ns.html?id=GTM-PWV3TKM" width="0" height="0" style="display:none; visibility:hidden"></iframe></noscript> <script>(function(w,d,s,l,i){w[l]=w[l]||[];w[l].push({'gtm.start':new Date().getTime(),event:'gtm.js'});var f=d.getElementsByTagName(s)[0],j=d.createElement(s),dl=l!='dataLayer'?'&l='+l:'';j.async=true;j.src='//www.googletagmanager.com/gtm.js?id='+i+dl;f.parentNode.insertBefore(j,f);})(window,document,'script','dataLayer','GTM-PWV3TKM');</script> <script type="application/ld+json"> { "@context": "http://schema.org", "@type": "Organization", "url": "https://postmarkapp.com", "logo": "https://postmarkapp.com/images/logo-stamp-social.png", "name": "Postmark", "founder": [ { "@type": "Person", "name": "Jason VandeBoom", "jobTitle": "CEO" } ], "foundingLocation": { "@type": "Place", "address": { "@type": "PostalAddress", "streetAddress": "1 North Dearborn St, 5th Floor", "addressLocality": "Chicago", "addressRegion": "IL", "postalCode": "60602", "addressCountry": "US" } }, "location": { "@type": "Place", "address": { "@type": "PostalAddress", "streetAddress": "1 North Dearborn St, 5th Floor", "addressLocality": "Chicago", "addressRegion": "IL", "postalCode": "60602", "addressCountry": "US" } }, "sameAs": [ "https://twitter.com/postmarkapp" ] } </script> <script type="application/ld+json"> { "@context": "http://schema.org", "@type": "WebSite", "name": "Postmark", "url": "https://postmarkapp.com" } </script> </body> </html>