Linux Mint

How to Install Seamonkey on Linux Mint 22 and 21

Last updated Saturday, June 6, 2026 9:40 am Joshua James 6 min read
Installing SeaMonkey Internet Suite on Linux Mint step by step.

Linux Mint does not ship a current SeaMonkey package in its default repositories, so the package source matters before installation. The suite still fills a useful niche when you want browsing, mail, IRC, and Composer in one application instead of four separate installs. To install SeaMonkey on Linux Mint 22.x or 21.x on a 64-bit x86 system, use the community-maintained Ubuntuzilla APT repository so updates stay inside normal package management.

The official SeaMonkey Linux x64 download is useful when you deliberately want a manual tarball install outside APT, but updates and cleanup stay in your hands. Ubuntuzilla packages the suite as seamonkey-mozilla-build, while the terminal command stays seamonkey and the menu entry appears as Mozilla Build of Seamonkey.

Install SeaMonkey on Linux Mint

Open a terminal from the applications menu, then work through this single APT method. The repository layout is version-agnostic, so the same commands apply to supported 64-bit Linux Mint 22.x and 21.x installs.

Check for an existing SeaMonkey install

Check whether SeaMonkey is already available before you add a third-party source:

command -v seamonkey && seamonkey --version

Installed systems return a binary path and version string like this. No output usually means SeaMonkey is not installed yet.

/usr/bin/seamonkey
Mozilla SeaMonkey 2.53.23

If you see that output, SeaMonkey is already installed; use the update commands when you want a newer build, or open it from the menu when you only need to start the suite.

Confirm the supported SeaMonkey package architecture

Ubuntuzilla provides SeaMonkey packages for 64-bit x86 Linux Mint systems. Check the local APT architecture before adding the repository:

dpkg --print-architecture
amd64

Continue only when the output is amd64. Do not continue on arm64 or aarch64 systems because the Ubuntuzilla SeaMonkey package index does not provide that architecture.

Prepare Linux Mint for the SeaMonkey repository

Refresh package metadata before installing repository helper packages:

sudo apt update

These steps use sudo when they need administrator privileges. If your Linux Mint account is not in the sudoers file yet, create a sudo-capable user on Linux Mint before continuing.

Next, install the packages needed for HTTPS downloads, certificate trust, and GnuPG key management:

sudo apt install ca-certificates curl gpg

Fetch the Ubuntuzilla signing key

Ubuntuzilla signs its packages, but it does not publish a project-hosted HTTPS key file. Download the key into a temporary directory, convert it locally, and install the final keyring with root-owned permissions. The subshell keeps the cleanup trap local to this key setup step.

(
  key_tmp="$(mktemp -d)"
  trap 'rm -rf "$key_tmp"' EXIT
  curl -fsSLo "$key_tmp/ubuntuzilla.asc" 'https://keyserver.ubuntu.com/pks/lookup?op=get&search=0xC77205F7194A3E1ABE2DF9A4B7B9C16F2667CA5C'
  gpg --dearmor --yes -o "$key_tmp/ubuntuzilla.gpg" "$key_tmp/ubuntuzilla.asc"
  sudo install -m 0644 "$key_tmp/ubuntuzilla.gpg" /usr/share/keyrings/ubuntuzilla.gpg
)

Verify that the saved keyring matches the expected Ubuntuzilla signing-key fingerprint:

gpg --quiet --show-keys --with-fingerprint /usr/share/keyrings/ubuntuzilla.gpg
pub   rsa8192 2016-11-12 [SC]
      C772 05F7 194A 3E1A BE2D  F9A4 B7B9 C16F 2667 CA5C
uid                      Daniel Folkinshteyn (Ubuntuzilla signing key) <nanotube@users.sourceforge.net>
sub   rsa8192 2016-11-12 [E]

Add the Ubuntuzilla repository for SeaMonkey

Create a dedicated DEB822 source file for the SeaMonkey package:

case "$(dpkg --print-architecture)" in
  amd64)
    printf '%s\n' \
    'Types: deb' \
    'URIs: https://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt' \
    'Suites: all' \
    'Components: main' \
    'Architectures: amd64' \
    'Signed-By: /usr/share/keyrings/ubuntuzilla.gpg' | sudo tee /etc/apt/sources.list.d/ubuntuzilla.sources > /dev/null
    ;;
  *)
    printf 'Ubuntuzilla currently provides the SeaMonkey package for amd64 Linux Mint systems only.\n' >&2
    false
    ;;
esac

This uses tee because plain > redirection would still run as your regular user and fail to write under /etc/apt/sources.list.d/. The .sources file keeps the repository in the current DEB822 format, Suites: all is intentional because Ubuntuzilla publishes one generic repository layout for both Mint 22.x and 21.x, and the architecture guard stops unsupported systems before they write a source that cannot provide the package.

Refresh APT and confirm the SeaMonkey package candidate before you install it:

sudo apt update
apt-cache policy seamonkey-mozilla-build
seamonkey-mozilla-build:
  Installed: (none)
  Candidate: 2.53.23-0ubuntu1
  Version table:
     2.53.23-0ubuntu1 500
        500 https://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt all/main amd64 Packages

APT refers to the package as seamonkey-mozilla-build, but the command and desktop launcher stay seamonkey.

Do not download a SeaMonkey DEB package, or .deb file, directly for a normal install. Using the repository keeps the signing key, package metadata, and future updates tied to APT instead of leaving a one-off local package behind.

Install the SeaMonkey package

Once APT sees the package candidate, install SeaMonkey from the Ubuntuzilla repository:

sudo apt install seamonkey-mozilla-build

Verify the SeaMonkey installation

Confirm that the binary is on your path and that the installed build responds normally:

command -v seamonkey && seamonkey --version
/usr/bin/seamonkey
Mozilla SeaMonkey 2.53.23

Launch SeaMonkey on Linux Mint

SeaMonkey adds a menu launcher and can also be started from the terminal when you want to see startup messages directly.

Open SeaMonkey from the Linux Mint menu

Open the application menu, search for SeaMonkey or Mozilla Build of Seamonkey, and launch the suite from there if you prefer the normal desktop workflow.

Linux Mint application menu showing the Mozilla Build of Seamonkey desktop entry selected.
Launch SeaMonkey from the Linux Mint application menu when you want the normal desktop entry.

Open SeaMonkey from the terminal

The terminal launch path is useful when you are testing profile changes or want to catch startup errors in the shell:

seamonkey

The first successful start creates your profile under ~/.mozilla/seamonkey, which is also the directory you back up or remove later.

Use SeaMonkey’s Built-In Tools on Linux Mint

SeaMonkey still bundles several classic Mozilla tools in one profile. That matters if you want the browser, Mail and Newsgroups, ChatZilla, and Composer living in the same application instead of as separate installs.

Understand SeaMonkey ports on Linux Mint

SeaMonkey does not install a background service or listen on a fixed local port. The package adds a desktop application only; web, mail, newsgroup, and IRC traffic uses outbound connections based on the account or server you configure. You normally do not need a Linux Mint firewall rule just to install or open SeaMonkey.

Set up SeaMonkey Mail and Newsgroups

Open Window > Mail & Newsgroups to start account setup. SeaMonkey supports IMAP, POP3, SMTP, and newsgroups, and modern providers such as Gmail or Outlook usually expect an app-specific password rather than your regular account password. Keep SSL or TLS enabled in the account settings so mail traffic stays encrypted.

Open SeaMonkey Composer on Linux Mint

Open Window > Composer when you want the built-in HTML editor. Composer is still useful for quick static pages, email templates, or light HTML and CSS edits when opening a full IDE would be overkill.

Back up the SeaMonkey profile directory

SeaMonkey stores bookmarks, mail data, account settings, and other profile content in ~/.mozilla/seamonkey. If you rely on the suite for mail or saved logins, back up that directory before major upgrades or before testing an upstream tarball build.

Update SeaMonkey on Linux Mint

Once Ubuntuzilla is configured, SeaMonkey updates like any other APT-managed package. Use a targeted upgrade when you want to refresh SeaMonkey without upgrading everything else at the same time:

Upgrade SeaMonkey with APT

sudo apt install --only-upgrade seamonkey-mozilla-build

Check the version afterward if you want to confirm the current build:

seamonkey --version
Mozilla SeaMonkey 2.53.23

Remove SeaMonkey from Linux Mint

Removing SeaMonkey cleanly takes three parts: purge the package, remove the Ubuntuzilla repository, and delete the profile directory if you do not want to keep personal data.

Purge the SeaMonkey package

Start by removing the package itself:

sudo apt purge seamonkey-mozilla-build

This removes the installed program and system-side package data, but it does not touch your personal SeaMonkey profile.

Remove the Ubuntuzilla repository

Delete the repository file and key so future apt update runs stop querying Ubuntuzilla:

sudo rm -f /etc/apt/sources.list.d/ubuntuzilla.sources
sudo rm -f /usr/share/keyrings/ubuntuzilla.gpg
sudo apt update

Delete SeaMonkey user data

This step permanently deletes your local SeaMonkey data, including bookmarks, mail, account settings, and saved profile content. Back up ~/.mozilla/seamonkey first if you want to keep any of it.

find "$HOME/.mozilla" -maxdepth 1 -type d -name 'seamonkey*' -print 2>/dev/null

No output means there is no matching SeaMonkey profile directory for the current account. Remove the profile only after you confirm that the listed path is safe to delete:

rm -rf "$HOME/.mozilla/seamonkey"

Verify SeaMonkey removal

Check both the package state and the launcher path so you know the suite is gone and not just missing from the current shell session:

if dpkg-query -W -f='${db:Status-Abbrev}\n' seamonkey-mozilla-build 2>/dev/null | grep -Eq '^(ii|rc)'; then
  dpkg-query -W -f='${db:Status-Abbrev} ${Package}\n' seamonkey-mozilla-build
else
  echo "package status: not installed"
fi
hash -r
command -v seamonkey || echo "seamonkey not found"
package status: not installed
seamonkey not found

Troubleshoot SeaMonkey on Linux Mint

Most SeaMonkey install problems on Linux Mint come down to key import failures, an inactive Ubuntuzilla source file, or a broken profile. These checks help isolate each case quickly.

Fix Ubuntuzilla key download errors

If the key download fails, first confirm that curl, certificate trust, and gpg are installed:

sudo apt install ca-certificates curl gpg

Then recreate the keyring through the HTTPS keyserver lookup URL:

(
  key_tmp="$(mktemp -d)"
  trap 'rm -rf "$key_tmp"' EXIT
  curl -fsSLo "$key_tmp/ubuntuzilla.asc" 'https://keyserver.ubuntu.com/pks/lookup?op=get&search=0xC77205F7194A3E1ABE2DF9A4B7B9C16F2667CA5C'
  gpg --dearmor --yes -o "$key_tmp/ubuntuzilla.gpg" "$key_tmp/ubuntuzilla.asc"
  sudo install -m 0644 "$key_tmp/ubuntuzilla.gpg" /usr/share/keyrings/ubuntuzilla.gpg
)

Confirm the saved keyring before retrying the APT refresh:

gpg --quiet --show-keys --with-fingerprint /usr/share/keyrings/ubuntuzilla.gpg
pub   rsa8192 2016-11-12 [SC]
      C772 05F7 194A 3E1A BE2D  F9A4 B7B9 C16F 2667 CA5C
uid                      Daniel Folkinshteyn (Ubuntuzilla signing key) <nanotube@users.sourceforge.net>
sub   rsa8192 2016-11-12 [E]

This path avoids the older keyserver helper ports and uses normal HTTPS. If curl still fails, check DNS, proxy, or TLS inspection on the network before repeating the repository setup.

Fix missing SeaMonkey package candidates

If apt says it cannot locate seamonkey-mozilla-build, verify that the DEB822 source file is present, refresh APT, and then check whether the package candidate is visible again. Relevant output includes:

cat /etc/apt/sources.list.d/ubuntuzilla.sources
sudo apt update
apt-cache policy seamonkey-mozilla-build
Types: deb
URIs: https://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt
Suites: all
Components: main
Architectures: amd64
Signed-By: /usr/share/keyrings/ubuntuzilla.gpg
seamonkey-mozilla-build:
  Installed: (none)
  Candidate: 2.53.23-0ubuntu1
  Version table:
     2.53.23-0ubuntu1 500
        500 https://downloads.sourceforge.net/project/ubuntuzilla/mozilla/apt all/main amd64 Packages

Reset a broken SeaMonkey profile

If SeaMonkey opens with a corrupted profile or the first-run setup never finishes cleanly, move the old profile out of the way and let SeaMonkey generate a fresh one:

if [ -d "$HOME/.mozilla/seamonkey" ]; then
  mv "$HOME/.mozilla/seamonkey" "$HOME/.mozilla/seamonkey.backup.$(date +%Y%m%d-%H%M%S)"
else
  echo "SeaMonkey profile directory not found"
fi

Relaunch SeaMonkey after that move. If the application starts normally, you can copy specific mail or bookmark data back from the backup directory instead of restoring the whole broken profile.

Conclusion

SeaMonkey now runs on Linux Mint with APT handling future updates, while the browser, mail, IRC, and Composer tools stay together in one profile. If you later decide you only need a browser, you can also install Chromium Browser on Linux Mint or install Tor Browser on Linux Mint.

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