sieve-library

Snippet library of validated Sieve email filters (RFC 5228).

Installation

You will need the pg_config binary to instal the necessary Postgres libraries. On Fedora, you can install this with the following command:

sudo dnf install libpq-devel

pip3 -m venv venv
source venv/bin/activate
pip3 install -r requirements.txt

docker-compose up -d

Usage

make

Design Philosophy

• When in doubt, default to expiring emails. Few things truly need to be kept indefinitely.
  • As of 03-18-2021, ProtonMail supports an undocumented maximum expiration of 120 days. Setting a value greater than 120 days will be silently accepted with no server side errors, defaulting to the max of 120 days. Keep this in mind.
  • Avoid using a global expiration rule with an "opt-in" model for retention. Emails are too unpredictable - it's a delicate balance.
  • Biannual offsite backups should address what concerns may arise from this strategy.
• Scheduled/routine emails of importance (example - daily finance updates) should route to the main inbox, but expire quickly.
• Keep it simple and avoid having too many folders and labels.
  • A doctors appointment email and a restaurant reservation email can go to the same folder, and that's okay.
  • Normal humans can hold 5-9 items in their working memory... 6 is a perfect number.
  • Nest where necessary
• No organizational system will ever be perfect. Expect and accept occasional inefficiencies.
• Think carefully about the execution chain. Use stops when warranted.
• Use subject header parsing with caution, but don't be afraid. It's an immensely powerful routing mechanism.
• IMAP uses modified UTF-7. Ensure folder and label names are in the US-ASCII range.
• You can only test so much before going to "prod". Ensure sieves handling ~critical emails explicitly check for and resolve unintended states, such as expirations.

Useful Links

• ProtonMail Sieve Docs
• Sieve Tutorial
• Official Sieve Wiki
• Sieve Language RFC
• IMAP RFC
• Sieve in Rust
• check-sieve
• an inspiration for this repo

Testing

• Supply .eml samples for unit testing
  • Ensure NO personally identifiable information is pasted into this tool.
• Pro Tip - this app is not aware of the "vnd.proton.expire" package. Remove it when testing with this app.
• When adding the sieve to ProtonMail, basic linting is performed server-side.

Deployment

• Manually copy and paste the definitions into ProtonMail Filters
  • "Ads" sieve is executed 1st (00)
  • "Security" sieve is executed 2nd (01)
  • "Statements" sieve is executed 3rd (02)
  • "Orders and Shipping" sieve is executed last (zz)

To Do

• Improve local testing by hooking up sieve script editor to docker-mailserver [local dev]
• Add Travis PR tests which check for syntax errors [CI]
  • Can likely have Travis run docker-mailserver and load the sieve filters into memory. Needs further investigation.
• Create test suite with mock email data (CI)
• Automate deployments [CD]
  • This is high LOE and has significant security implications.