{"id":112661,"date":"2026-11-03T17:03:29","date_gmt":"2026-11-03T17:03:29","guid":{"rendered":"https:\/\/mailrelay.com\/glossary\/thunderbird\/"},"modified":"2026-11-03T17:03:32","modified_gmt":"2026-11-03T17:03:32","slug":"thunderbird","status":"publish","type":"glossary","link":"https:\/\/mailrelay.com\/en\/glossary\/thunderbird\/","title":{"rendered":"Thunderbird"},"content":{"rendered":"\n<p class=\"wp-block-paragraph\">Thunderbird is a free, open-source email client created by Mozilla that brings your email accounts, calendar and contacts together in a single application.<\/p>\n\n<p class=\"wp-block-paragraph\">Here&#8217;s what it offers, how to set up your accounts, which versions there are and the most common problems.<\/p>\n\n<h2 class=\"wp-block-heading\">What is Thunderbird?<\/h2>\n\n<p class=\"wp-block-paragraph\">It&#8217;s an <a href=\"https:\/\/mailrelay.com\/en\/blog\/2026\/04\/03\/email-clients\/\" target=\"_blank\" rel=\"noopener\">email client<\/a> you install on your computer to read and send emails from any provider, without relying on your browser. Its first version came out in 2003, and it&#8217;s the email &#8220;sibling&#8221; of the Firefox browser.<\/p>\n\n<p class=\"wp-block-paragraph\">Today it&#8217;s developed by MZLA Technologies, a subsidiary of the Mozilla Foundation, and it&#8217;s funded mainly through donations. It doesn&#8217;t show ads or sell your data.<\/p>\n\n<p class=\"wp-block-paragraph\">It runs on Windows, macOS and Linux. Since 2024 it has also had an Android app, based on K-9 Mail, and the iPhone app is in testing.<\/p>\n\n<h2 class=\"wp-block-heading\">What is Thunderbird used for?<\/h2>\n\n<p class=\"wp-block-paragraph\">To keep everything in one place:<\/p>\n\n<ul class=\"wp-block-list\">\n<li><strong>Several email accounts<\/strong> at once: <a href=\"https:\/\/mailrelay.com\/en\/glossary\/gmail-email\/\" target=\"_blank\" rel=\"noopener\">Gmail<\/a>, <a href=\"https:\/\/mailrelay.com\/en\/glossary\/outlook\/\" target=\"_blank\" rel=\"noopener\">Outlook<\/a>, <a href=\"https:\/\/mailrelay.com\/en\/glossary\/icloud-mail\/\" target=\"_blank\" rel=\"noopener\">iCloud Mail<\/a>, your work email or your internet provider&#8217;s.<\/li>\n\n\n\n<li><strong>Calendar and contacts<\/strong> synced with those accounts.<\/li>\n\n\n\n<li><strong>Filters and tags<\/strong> to organize your <a href=\"https:\/\/mailrelay.com\/en\/glossary\/inbox\/\" target=\"_blank\" rel=\"noopener\">inbox<\/a>, and a <a href=\"https:\/\/mailrelay.com\/en\/glossary\/spam\/\" target=\"_blank\" rel=\"noopener\">spam<\/a> filter that learns from what you mark.<\/li>\n\n\n\n<li><strong>Built-in OpenPGP encryption<\/strong> to sign and encrypt your messages.<\/li>\n\n\n\n<li><strong>RSS news reader<\/strong> and add-ons for extra features.<\/li>\n<\/ul>\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune-1024x576.png\" alt=\"What Thunderbird brings together in one program: several email accounts, calendar, contacts, filters and tags, OpenPGP encryption and an RSS reader\" class=\"wp-image-112617\" srcset=\"https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune-1024x576.png 1024w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune-300x169.png 300w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune-768x432.png 768w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune-1536x864.png 1536w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune-110x62.png 110w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune-60x34.png 60w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-que-reune.png 1672w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n<p class=\"wp-block-paragraph\">If you use several addresses, it&#8217;s more convenient than opening a separate <a href=\"https:\/\/mailrelay.com\/en\/glossary\/webmail\/\" target=\"_blank\" rel=\"noopener\">webmail<\/a> for each one.<\/p>\n\n<div class=\"wp-block-group has-very-light-gray-background-color has-background\" style=\"border-radius:8px;padding-top:24px;padding-right:28px;padding-bottom:24px;padding-left:28px\"><div class=\"wp-block-group__inner-container is-layout-flow wp-block-group-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Do you send emails to your customers from Thunderbird?<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">With Mailrelay you send your newsletters to your whole list, without your email account&#8217;s limits, with statistics and automatic unsubscribes. Free account with up to 80,000 emails a month.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button is-style-mailrelay-primary-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/mailrelay.com\/en\/signup\/?utm_medium=cta&#038;utm_campaign=thunderbird\">Create a free account<\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n<h2 class=\"wp-block-heading\">How do you set up an account in Thunderbird?<\/h2>\n\n<p class=\"wp-block-paragraph\">In most cases, it does it on its own:<\/p>\n\n<ol class=\"wp-block-list\">\n<li>Download Thunderbird from its official website and install it.<\/li>\n\n\n\n<li>Enter your name, your address and your password.<\/li>\n\n\n\n<li>The program looks up your provider&#8217;s settings and suggests <a href=\"https:\/\/mailrelay.com\/en\/glossary\/imap\/\" target=\"_blank\" rel=\"noopener\">IMAP<\/a> or <a href=\"https:\/\/mailrelay.com\/en\/glossary\/pop3\/\" target=\"_blank\" rel=\"noopener\">POP3<\/a>.<\/li>\n\n\n\n<li>If your provider requires it, sign in in the window that opens in your browser.<\/li>\n\n\n\n<li>Confirm and wait for your messages to download.<\/li>\n<\/ol>\n\n<p class=\"wp-block-paragraph\">Choose IMAP if you read your email on several devices. POP3 downloads messages to a single computer.<\/p>\n\n<h2 class=\"wp-block-heading\">How to set up Gmail, Outlook and other providers<\/h2>\n\n<p class=\"wp-block-paragraph\">Each provider has its own quirks:<\/p>\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Provider<\/th><th>What to keep in mind<\/th><\/tr><\/thead><tbody><tr><td>Gmail<\/td><td>Sets itself up with OAuth2: you sign in with your Google account<\/td><\/tr><tr><td>Outlook and Hotmail<\/td><td>Uses OAuth2 on the incoming server and on <a href=\"https:\/\/mailrelay.com\/en\/glossary\/smtp\/\" target=\"_blank\" rel=\"noopener\">SMTP<\/a>. Your regular password no longer works<\/td><\/tr><tr><td>Exchange (business)<\/td><td>Recent versions support it natively, without add-ons<\/td><\/tr><tr><td>iCloud Mail<\/td><td>You need an app-specific password<\/td><\/tr><tr><td><a href=\"https:\/\/mailrelay.com\/en\/glossary\/protonmail\/\" target=\"_blank\" rel=\"noopener\">Proton Mail<\/a><\/td><td>Only with Proton Mail Bridge, on paid plans<\/td><\/tr><tr><td>Your own domain&#8217;s email<\/td><td>Ask your hosting provider for its <a href=\"https:\/\/mailrelay.com\/en\/glossary\/email-server\/\" target=\"_blank\" rel=\"noopener\">email server<\/a> details<\/td><\/tr><\/tbody><\/table><\/figure>\n\n<p class=\"wp-block-paragraph\">If the wizard can&#8217;t find the settings, choose manual configuration and enter your provider&#8217;s servers, ports and encryption type.<\/p>\n\n<h2 class=\"wp-block-heading\">Which versions are there? Release and ESR<\/h2>\n\n<p class=\"wp-block-paragraph\">There are two update channels, and both are free:<\/p>\n\n<figure class=\"wp-block-table\"><table class=\"has-fixed-layout\"><thead><tr><th>Channel<\/th><th>Updates<\/th><th>Who it&#8217;s for<\/th><\/tr><\/thead><tbody><tr><td>Release<\/td><td>A new version every month<\/td><td>People who want new features sooner<\/td><\/tr><tr><td>ESR (Extended Support Release)<\/td><td>One major version a year<\/td><td>Businesses and people who prefer stability<\/td><\/tr><\/tbody><\/table><\/figure>\n\n<p class=\"wp-block-paragraph\">The latest ESR is Thunderbird 153 &#8220;Meadow&#8221;, from July 2026, with a redesigned account setup wizard.<\/p>\n\n<p class=\"wp-block-paragraph\">Mozilla is also preparing Thunderbird Pro, a paid service with its own email (Thundermail), which has been in beta since 2026. The program itself remains free.<\/p>\n\n<h2 class=\"wp-block-heading\">Common problems and how to fix them<\/h2>\n\n<p class=\"wp-block-paragraph\"><strong>I can&#8217;t connect my Outlook account.<\/strong> Change the authentication method to OAuth2 on both the incoming and outgoing servers.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>It doesn&#8217;t send emails.<\/strong> Check that the outgoing server&#8217;s port and encryption match, and that SMTP requires authentication.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>The program is slow.<\/strong> Compact your folders and empty the trash. If you have many years of email, archive the old messages.<\/p>\n\n<p class=\"wp-block-paragraph\"><strong>I want to switch computers.<\/strong> Copy your profile folder or use the program&#8217;s own export tool.<\/p>\n\n<h2 class=\"wp-block-heading\">Can you use Thunderbird to send newsletters?<\/h2>\n\n<p class=\"wp-block-paragraph\">For a few recipients, yes, with a <a href=\"https:\/\/mailrelay.com\/en\/glossary\/mail-merge\/\" target=\"_blank\" rel=\"noopener\">mail merge<\/a> add-on. But it has the same limits as the account you send from.<\/p>\n\n<p class=\"wp-block-paragraph\">Gmail, Outlook or your internet provider limit how many emails you can send per day, and large sends from a personal account end up blocked. Check each provider&#8217;s <a href=\"https:\/\/mailrelay.com\/en\/glossary\/sending-limits\/\" target=\"_blank\" rel=\"noopener\">sending limits<\/a>.<\/p>\n\n<figure class=\"wp-block-image size-large\"><img loading=\"lazy\" decoding=\"async\" width=\"1024\" height=\"576\" src=\"https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing-1024x576.png\" alt=\"Sending newsletters: Thunderbird vs. an email marketing tool, with your email account's limits and no statistics vs. sends to your whole list with opens, clicks and automatic unsubscribes\" class=\"wp-image-112621\" srcset=\"https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing-1024x576.png 1024w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing-300x169.png 300w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing-768x432.png 768w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing-1536x864.png 1536w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing-110x62.png 110w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing-60x34.png 60w, https:\/\/mailrelay.com\/wp-content\/uploads\/2026\/11\/thunderbird-vs-herramienta-email-marketing.png 1672w\" sizes=\"auto, (max-width: 1024px) 100vw, 1024px\" \/><\/figure>\n\n<p class=\"wp-block-paragraph\">You also won&#8217;t get open and click statistics or automatic unsubscribes. And if you CC everyone, each contact sees everyone else&#8217;s addresses. <a href=\"https:\/\/mailrelay.com\/en\/glossary\/cc-and-bcc\/\" target=\"_blank\" rel=\"noopener\">BCC<\/a> prevents that, but doesn&#8217;t solve the rest.<\/p>\n\n<p class=\"wp-block-paragraph\">That&#8217;s what <a href=\"https:\/\/mailrelay.com\/en\/blog\/2022\/11\/08\/how-to-send-a-newsletter-a-step-by-step-guide\/\" target=\"_blank\" rel=\"noopener\">bulk email<\/a> tools are for.<\/p>\n\n<h2 class=\"wp-block-heading\">How Mailrelay helps you<\/h2>\n\n<p class=\"wp-block-paragraph\">Mailrelay and Thunderbird complement each other. You keep using Thunderbird for your everyday email, and you send your newsletters from Mailrelay with the same address and an authenticated <a href=\"https:\/\/mailrelay.com\/en\/glossary\/sending-domain\/\" target=\"_blank\" rel=\"noopener\">sending domain<\/a>.<\/p>\n\n<p class=\"wp-block-paragraph\">The <a href=\"https:\/\/mailrelay.com\/en\/glossary\/free-mailing\/\" target=\"_blank\" rel=\"noopener\">free account<\/a> includes up to 80,000 emails a month and 20,000 contacts.<\/p>\n\n<p class=\"wp-block-paragraph\">You get a visual editor, automations, open and click statistics, and automatic management of unsubscribes and bounces, with human support on every plan. All the details are on the <a href=\"https:\/\/mailrelay.com\/en\/pricing\/\" target=\"_blank\" rel=\"noopener\">pricing<\/a> page.<\/p>\n\n<div class=\"wp-block-group has-very-light-gray-background-color has-background\" style=\"border-radius:8px;padding-top:24px;padding-right:28px;padding-bottom:24px;padding-left:28px\"><div class=\"wp-block-group__inner-container is-layout-flow wp-block-group-is-layout-flow\">\n<p class=\"wp-block-paragraph\"><strong>Thunderbird for your email, Mailrelay for your newsletters<\/strong><\/p>\n\n\n\n<p class=\"wp-block-paragraph\">Templates, automations and statistics, with human support on every plan.<\/p>\n\n\n\n<div class=\"wp-block-buttons is-layout-flex wp-block-buttons-is-layout-flex\">\n<div class=\"wp-block-button is-style-mailrelay-primary-button\"><a class=\"wp-block-button__link wp-element-button\" href=\"https:\/\/mailrelay.com\/en\/signup\/?utm_medium=cta&#038;utm_campaign=thunderbird\">Try Mailrelay for free<\/a><\/div>\n<\/div>\n<\/div><\/div>\n\n<h2 class=\"wp-block-heading\">Thunderbird FAQ<\/h2>\n\n<p class=\"wp-block-paragraph\">These are the most common questions.<\/p>\n\n<h3 class=\"wp-block-heading\">Is Thunderbird free?<\/h3>\n\n<p class=\"wp-block-paragraph\">Yes. It&#8217;s free and open source, with no ads. It&#8217;s funded by donations from its users.<\/p>\n\n<h3 class=\"wp-block-heading\">Is Thunderbird safe?<\/h3>\n\n<p class=\"wp-block-paragraph\">Yes. It gets frequent security updates, blocks remote content in emails by default, warns you about messages that look like <a href=\"https:\/\/mailrelay.com\/en\/glossary\/phishing\/\" target=\"_blank\" rel=\"noopener\">phishing<\/a> and includes OpenPGP encryption.<\/p>\n\n<h3 class=\"wp-block-heading\">Thunderbird or Outlook?<\/h3>\n\n<p class=\"wp-block-paragraph\">Thunderbird is free and works the same with any provider. Outlook is a better fit if your company already works with <a href=\"https:\/\/mailrelay.com\/en\/glossary\/microsoft-365\/\" target=\"_blank\" rel=\"noopener\">Microsoft 365<\/a>.<\/p>\n\n<h3 class=\"wp-block-heading\">Is there Thunderbird for mobile?<\/h3>\n\n<p class=\"wp-block-paragraph\">Yes, for Android, since 2024. The iPhone version is in testing.<\/p>\n\n<h3 class=\"wp-block-heading\">Is Thunderbird made by Mozilla?<\/h3>\n\n<p class=\"wp-block-paragraph\">Yes. It&#8217;s developed by MZLA Technologies, a subsidiary of the Mozilla Foundation, the same organization behind Firefox.<\/p>\n\n<h2 class=\"wp-block-heading\">Related entries<\/h2>\n\n<ul class=\"wp-block-list\">\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/outlook\/\">Outlook<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/gmail-email\/\">Gmail<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/icloud-mail\/\">iCloud Mail<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/protonmail\/\">Proton Mail<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/webmail\/\">Webmail<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/imap\/\">IMAP<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/pop3\/\">POP3<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/smtp\/\">SMTP<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/email-server\/\">Email server<\/a><\/li>\n\n\n\n<li><a href=\"https:\/\/mailrelay.com\/en\/glossary\/mail-merge\/\">Mail merge<\/a><\/li>\n<\/ul>\n","protected":false},"template":"","class_list":["post-112661","glossary","type-glossary","status-publish","hentry"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v28.7 - 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