Thunderbird for iOS Settings: What You Can Change Now

Thunderbird for iOS is Mozilla’s email app for iPhone and iPad, and while it is still in its early stages, you can already adjust several key settings to control notifications, appearance, message actions, and account behavior. Right now, you can change notification sounds and badges, choose a default signature, set swipe actions, enable or disable message previews, and manage how often the app checks for new mail. Below is a detailed look at every setting available in the current version, plus what is still missing and how to work around it.

Background: Thunderbird’s Arrival on iOS

Mozilla released Thunderbird for iOS in 2024 as part of a broader effort to bring the desktop email client to mobile. The app is built on the open-source K-9 Mail project, which Mozilla acquired in 2022. Because it is a young app, it does not yet have every feature found in the desktop version, but the settings that exist are functional and updated regularly. The app is free, available on the App Store, and supports standard email protocols like IMAP and SMTP, as well as OAuth2 for Gmail and Outlook accounts.

Accessing the Settings Menu

To change any setting, open the app and tap the three-line menu icon in the top-left corner. Scroll to the bottom and tap Settings. From here, you can adjust global preferences that apply to all accounts, or tap a specific account to change its individual settings. The settings are grouped into logical sections, and most changes take effect immediately without needing to restart the app.

Notification Settings

The notification settings control how you are alerted to new messages. Under Settings > Notifications, you can:

Toggle New Mail Notifications on or off entirely.
Choose a sound from the iOS system list (default is “Tri-tone”).
Enable or disable badge app icon to show the unread count on the home screen.
Set notification preview to show the sender, subject, or full message content on the lock screen.

These settings apply globally to all accounts. If you want different notification behavior per account, you cannot do that yet – it is a known limitation. However, you can mute specific threads by opening a conversation and tapping the bell icon.

Appearance and Reading Settings

Under Settings > Appearance, you can change the app’s theme to Light, Dark, or System (which follows your device’s setting). You can also adjust the font size for the message list and reading pane. A notable setting here is Message Preview: you can choose to show 1, 2, or 3 lines of text in the message list, or turn it off entirely to show only the sender and subject.

There is also a Show Contact Photos toggle. When enabled, the app displays the sender’s avatar (if available) next to each message. Disabling it can make the list more compact.

Message Actions and Swipe Gestures

Thunderbird for iOS lets you customize swipe actions for the message list. Go to Settings > Message Actions and select either Left Swipe or Right Swipe. For each, you can choose from:

Archive
Delete
Mark as Read/Unread
Move to folder
Flag

By default, left swipe deletes and right swipe archives. You can also set a long press action to quickly access a menu of all actions. This is one of the most useful settings for tailoring the app to your workflow.

Composing and Signature Settings

When composing a new message, you can change the default signature under Settings > Signature. You can set a global signature that applies to all accounts, or override it per account by tapping the account name and then Signature. The signature is plain text only – no rich formatting or images – and it is inserted automatically when you start a new message.

There is also a Reply/Forward setting that lets you choose whether replies are quoted above or below the original message. You can also set the default message format to HTML or Plain Text. If you send plain text, the app will not include HTML formatting, which can be important for newsletters or technical lists.

Account-Level Settings

Each email account has its own settings page, accessible from the main Settings screen by tapping the account name. Here you can:

Change the display name and email address used in outgoing messages.
Set the sync frequency (every 15 minutes, 30 minutes, hourly, or manually).
Enable push if your provider supports it (Gmail and Outlook do).
Choose which folders to sync (Inbox, Sent, Drafts, etc.) and how many days of messages to keep offline.
Set the trash and archive folders – important if your provider uses non-standard names.

These account settings give you granular control over data usage and storage. For example, if you have limited phone storage, you can set “Sync messages from the last 1 month” instead of “All messages.”

Frequently Asked Questions

Can I change the default folder when I swipe to archive?

Yes, you can. Under Settings > Message Actions, when you choose “Move to folder” as a swipe action, the app will ask you to select the destination folder the first time you use it. That folder becomes the default for that swipe until you change it again.

Why don’t I see a “Mark all as read” button?

That feature is not yet available in the iOS app. As a workaround, you can select multiple messages by tapping the edit icon in the top-right of the message list, then tap “Mark read” at the bottom. This works for the entire folder if you select all.

Does Thunderbird for iOS support Face ID or Touch ID lock?

Not yet. The app does not have a built-in app lock. You can use iOS Screen Time to restrict access, but that is a system-level workaround, not an in-app setting.

Can I set different notification sounds for different accounts?

No, notification sounds are global. However, you can set different vibration patterns if you use the iOS Accessibility settings, but that is not per-account either. This is a commonly requested feature that Mozilla has said they are considering.

How do I change the font size in Thunderbird for iOS?

Go to Settings > Appearance > Font Size. You can drag the slider to make text larger or smaller. This affects both the message list and the reading pane.

Is there a dark mode that follows the system?

Yes, under Settings > Appearance > Theme, choose “System” to automatically switch between light and dark based on your device’s setting. You can also force it to always be light or dark.

What You Cannot Change Yet

Thunderbird for iOS is missing a few settings that desktop users might expect. There is no option to change the swipe sensitivity, no per-folder notification rules, and no custom swipe actions beyond the listed ones. Also, you cannot set a default “send from” address when you have multiple aliases – you must select it manually each time. Mozilla’s public roadmap indicates that more settings are planned, including a unified inbox toggle and a “smart folders” feature, but these are not available in the current App Store version.

If you need a setting that is not there, the best approach is to send feedback through the app’s Help > Send Feedback menu. Mozilla actively uses this feedback to prioritize new features.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

More in this bed

The whole Tech How-To bed →