Thunderbird add-on: Auto Archive by Date

A free add-on for Mozilla Thunderbird that automatically moves old emails into structured backup folders – keeping your profile lean without deleting messages.

Download add-on (current version) Currently: version 3.2.0 – it is recommended that auto-archive-latest.xpi always points to the most recent build on the server.

For documentation or reproducible setups you may additionally provide the concrete build: Download v3.2.0.

What the add-on does

Auto Archive by Date moves old emails out of your active Thunderbird profile into a dedicated archive area. You define a cut-off date – for example 1 January 2022 – and the add-on moves all messages before that date into your chosen backup folder, optionally split by year.

Your existing folder and subfolder structure is preserved, so you can keep your day-to-day mailbox lean without losing historical information or having to search through a huge single folder.

Key properties

• Archiving based on a configurable cut-off date
• Optional per-year subfolders (2022, 2021, …) for better overview
• Per-account archive folders plus a global fallback option
• Two-phase workflow: Preview → Execute
• Configurable safety buffer in days (default: 7)
• Limit per run so you don't move “too much at once”
• Optional dry-run mode without real changes
• Automatic CSV log after each real run

Important: Emails are moved, never deleted. They remain fully accessible and searchable in Thunderbird – just in a different folder.

Installation in Thunderbird

1. Save the file auto-archive-latest.xpi locally on your machine.
2. Open Thunderbird and go to Tools → Add-ons and Themes (or main menu ☰ → Add-ons and Themes).
3. Click the small gear icon and choose “Install Add-on from file…”.
4. Select the XPI file and confirm the installation.
5. Restart Thunderbird if requested.

After installation, you will find the add-on in the Add-ons manager. There you can configure cut-off date, target folders, buffer zone, per-run limit and logging options.

Typical use cases

• You have been using the same profile for years and Thunderbird feels slow.
• Your inbox is full of old system or informational messages you rarely need.
• You want to keep emails long-term, but outside your daily working folders, in a dedicated archive area.

Changelog (short)

Technical details & compatibility

• Thunderbird versions: primarily tested with 115.x (ESR, “Supernova”) in 64-bit builds
• Operating systems:
  • Windows 10/11 (64-bit)
  • Linux (x86_64, recent distributions)
  • macOS (from roughly version 12 upwards, 64-bit)
• Limitations: no dedicated tests in enterprise environments with roaming profiles or heavily customised policies
• Profile location: standard Thunderbird profiles; the exact path depends on the operating system
• Log format: CSV (UTF-8 with BOM), one line per move operation
• Performance note: for very large mailboxes it is recommended to start with a smaller per-run limit (e.g. 500–1000 messages) first.

If you run the add-on in a special environment (e.g. terminal server, roaming profiles, very large IMAP accounts), consider testing it first in a separate profile or a copy of your main profile before using it in production.

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