My personal sieve filters for use with ProtonMail. Sieves are commonly referred to as email filters.

While these are personal sieves, most of these are general purpose and can be modified/extended as needed.

Contributions are accepted.

• 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.
• No organizatonal 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.

• ProtonMail Sieve Docs
• Sieve Tutorial
• Official Sieve Wiki
• Sieve Language RFC
• IMAP RFC

• Web app for testing sieves
  • NOTE - ensure NO personaly 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.

• 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)

• 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 likey 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.