Knowledge Base

Ten practical jobs Sieve does on a Zimbra server every day: tag external mail, catch spoofed senders, sort mailing lists, handle attachments, auto-reply and more.

Ten ready-to-use Sieve scripts for Zimbra: file newsletters and invoices, flag mail from your manager, forward urgent messages, tag projects and more.

Learn how Zimbra uses Sieve for mail filters: the basic syntax, where scripts are stored, and how to set them up in the web client, admin console and CLI.

Every action a Zimbra Sieve filter can take: fileinto, discard, reject, redirect, tag, flag, reply, notify, header editing and logging, with syntax and Zimbra's own limits.

Every test a Zimbra Sieve filter can run on a message: header, address, envelope, size, body, plus Zimbra's own attachment, me, list, bulk, importance and time tests.

A step-by-step way to debug a Sieve filter on Zimbra: read the right log, turn on filter logging, make the script report what it did, and the silent failures to check.

Side-by-side tables of every MSH Zimbra Rules condition and action against its Sieve equivalent, and which of the two to reach for when both could do the job.

Mark every message from outside your organization with an [EXTERNAL] subject marker and a header, using one admin Sieve script applied to a whole domain.

Catch display-name spoofing and CEO fraud with an admin Sieve script that marks mail whose From header claims your domain or your staff but arrives from outside.

Use the X-Spam-Level and X-Spam-Score headers in a Sieve filter to send borderline mail to a review folder, and avoid the ascii-numeric trap that flags clean mail.

Four ways to stop unwanted mail with a Sieve filter - discard, reject, ereject and fileinto - and which one to pick so senders are not told what happened.

Use Zimbra's list and bulk Sieve tests, plus List-Id and variables, to file every mailing list and newsletter into folders without naming a single sender.

Use Zimbra's me test in a Sieve filter to split mail addressed directly to you from Cc traffic and invisible Bcc, so the Inbox holds only what needs an answer.

Turn on plus addressing with zimbraMtaRecipientDelimiter, then file each you+tag@ address into its own folder with a Sieve filter - and see who leaked your address.

Use Zimbra's attachment test and mime_header to file mail that carries documents, route PDFs and scans to folders, and refuse executable files at delivery.

Zimbra has no Sieve vacation command. Learn what its reply action does instead, how to stop it answering mailing lists, and when to use the built-in out-of-office.

File monitoring mail, backup reports and cron output with a Sieve filter that leaves the failures in the Inbox, so the messages that matter stop hiding in the noise.

What cbpolicyd is, where it came from, what state the project is in today, and what it is genuinely good at on a Zimbra server - rate limits, quotas and access control.

Turn cbpolicyd on, prove Postfix is really consulting it, then learn the policy model - policies, groups, members and priority - before writing your first rule.

Use the cbpolicyd quotas module to cap how much mail a sender, recipient or client network can push through Zimbra, with worked rules for the cases that matter.

Allow and deny mail during the SMTP session with the cbpolicyd access control module, including the verdicts available and when it beats a Postfix access map.

How greylisting works, how to configure it in cbpolicyd with auto-whitelisting, and the delay and deliverability trade-offs before you turn it on for a live domain.

Configure the cbpolicyd checkspf module to act on SPF results during the SMTP session, and understand why rejecting on SPF failure breaks forwarded mail.

Use the cbpolicyd checkhelo module to reject senders impersonating your server, catch HELO randomisation, and enforce RFC-compliant HELO names without losing real mail.

Track mail volume per day, week or month with the cbpolicyd accounting module, report on it with SQL, and understand how it differs from quotas.

What the cbpolicyd amavis module does, why it needs amavis pointed at the same database, and what to use instead on a Zimbra server where amavis is managed for you.

Why a cbpolicyd rule does nothing, fires on the wrong mail, or stops working - checked in the order that finds the cause fastest, with the SQL to prove each step.