Switch to Thunderbird: IMAP explained, and the settings you need

IMAP is the way of reading email that keeps your mail on the server, so your laptop, your phone and your webmail all show the same folders and the same messages. Thunderbird is a free, open-source email app that works with any IMAP mailbox, runs the same on Windows, macOS and Linux, and has OpenPGP encryption built in. It is the email app Noiz recommends. For a Noiz mailbox you need four settings: IMAP on port 993 and SMTP on port 465, both with SSL/TLS, your full email address as the username, and your mailbox password.

IMAP and POP: what the difference means for you

Two standards let an email app collect mail from a server.

• IMAP (defined today in RFC 9051) lets your app work with folders on the server as if they were on your own computer. The server copy is the master. Read a message on your phone and it shows as read on your laptop; file it in a folder and the folder is there on every device.
• POP3 (RFC 1939) was designed to download mail and then delete it from the server. The standard itself says it is not meant for managing mail on the server. Mail usually ends up on one device only.

For almost everyone, IMAP is the right choice. It suits more than one device, it keeps sent mail and folders in step, and losing a laptop does not mean losing your mail.

Why Noiz recommends Thunderbird

• It is free and open source. Thunderbird is made by MZLA Technologies, a subsidiary of the Mozilla Foundation, and its source code is public. Anyone can inspect what it does with your mail.
• It talks to your mail server directly. Thunderbird connects your computer to your mailbox with no third party in between. Some newer mail apps sync other providers' mailboxes through their own cloud instead; our article on how the new Outlook hands your mailbox to Microsoft explains why that matters.
• It uses open standards. IMAP and SMTP for mail, CalDAV and CardDAV for calendars and contacts. Nothing ties you to one provider.
• It has OpenPGP built in. You can sign and encrypt messages end to end without an add-on.
• It handles large mailboxes and many accounts. One unified inbox, tags, filters, saved searches, several identities and templates.
• It runs the same everywhere. The desktop app runs on Windows, macOS and Linux, so a mixed office uses one app. Thunderbird for Android, built from the K-9 Mail app, is available from Google Play and F-Droid. An iPhone app is in development and not yet released, as at October 2026.

The settings for a Noiz mailbox

Thunderbird can often find the settings itself when you enter your address and password. On custom domains that lookup can fail or find the wrong provider, so it helps to know the settings.

Replace yourdomain.com with your own domain. If Thunderbird warns about a certificate mismatch, use the mail server name from your Noiz welcome email instead.

These are the encrypted ports. The standard for mail submission, RFC 8314, says email apps should connect with TLS from the first byte in preference to upgrading a plain connection later, and ports 993 and 465 do exactly that. Do not use the unencrypted ports 143, 110 or 25.

Our help centre walks through each screen in how to set up email in Thunderbird.

Moving from another email app

You have two ways in.

1. Start clean on IMAP. Add the mailbox to Thunderbird and let it download the folders from the server. If you were already using IMAP elsewhere, everything is there.
2. Bring old mail with you. If your old app kept mail only on your computer, as POP3 set-ups often do, import it into Thunderbird first, then copy the folders you need into the IMAP mailbox so they live on the server too.

Our guide on why and how to switch to Thunderbird covers the import in more detail.

Settings worth changing on day one

• Leave remote content blocked. Images loaded from the web can tell a sender when and where you opened a message.
• Keep the junk filter on, and train it by marking what it misses.
• Keep strict certificate checking on, so Thunderbird refuses a server that is not who it claims to be.
• Set up folders and filters to sort mail as it arrives.
• Back up your Thunderbird profile, especially any local folders that live only on your computer.

Our help centre lists the best Thunderbird settings to configure first.

Add encryption with OpenPGP

Email crosses several servers on its way and is stored on each one in readable form. OpenPGP encrypts the message itself, so only the person holding the right key can read it. Thunderbird has it built in. Both you and the person you write to need keys, and the sender, recipient and date stay visible to the servers.

To start, follow our guides to setting up OpenPGP keys in Thunderbird and sending encrypted and signed email.

Your Noiz mailbox works with Thunderbird

Every Noiz shared hosting plan includes email with webmail, IMAP and SMTP, so Thunderbird works with your mailbox from day one. If something does not connect, open a ticket and we will check the settings with you. For mail on a server of its own, see Private Email.

Sources

Checked 19 October 2026.

Standards

• RFC 9051: IMAP version 4 revision 2
• RFC 1939: Post Office Protocol version 3
• RFC 8314: Cleartext considered obsolete

Thunderbird

• Thunderbird's new home (MZLA Technologies), 28 January 2020
• About Thunderbird
• Download Thunderbird
• Thunderbird for Android 8.0, 30 October 2024
• Thunderbird for iOS: a first look, 1 October 2026
• OpenPGP in Thunderbird: HOWTO and FAQ

Noiz

• Switch to Thunderbird (the original article, noiz.ie)
• New Outlook hands your mailbox to Microsoft
• How to Set Up Email in Thunderbird (Noiz help centre)
• Email hosting

Note: while some of this content was produced with the help of AI, the final editing has been done by a real human being.