Mbox Viewer’s search bar understands a compact query language modeled on the operators power users already know from Gmail. This cheat sheet covers every operator, how to combine them, and ready-to-use examples you can paste straight into the search field.

How search works

Type a query into the search bar and Mbox Viewer filters the open archive in real time — even across millions of messages. A bare word like invoice matches anywhere in the message. To be precise, add operators in the form field:value.

Operators are case-insensitive (From: and from: are identical).
Multiple terms are joined with AND by default.
There’s no need to re-index between searches; results update as you type.

Field operators

Operator	Matches	Example
`from:`	The sender address or name	`from:[email protected]`
`to:`	A recipient (To field)	`to:[email protected]`
`cc:`	A carbon-copy recipient	`cc:[email protected]`
`subject:`	Text in the subject line	`subject:invoice`
`body:`	Text in the message body only	`body:"wire transfer"`
`date:`	Messages on or around a date	`date:2025-03-14`
`has:attachment`	Messages that carry a file	`has:attachment`
`size:>`	Messages larger than a size	`size:>10mb`
`size:<`	Messages smaller than a size	`size:<100kb`

Combining terms

AND (the default)

Listing terms together requires all of them to match.

from:alice subject:report has:attachment

Finds messages from Alice, with “report” in the subject, that include an attachment.

OR

Use OR (uppercase) to match either term.

from:alice OR from:bob

Returns messages from Alice or Bob.

Negation

Prefix a term with - to exclude it.

subject:invoice -from:[email protected]

Finds invoice subjects but hides the automated no-reply sender.

Exact phrases

Wrap words in quotes to match the exact phrase in order.

subject:"final invoice 2025"

Without quotes, the words could appear separately and in any order.

Working with dates

The date: operator accepts ISO-style dates and ranges.

Goal	Query
A specific day	`date:2025-03-14`
On or after a date	`date:>=2025-01-01`
Before a date	`date:<2025-06-01`
A range	`date:2025-01-01..2025-03-31`

Working with size

Size filters accept kb, mb, and gb suffixes. They’re perfect for finding the heavy messages eating up your archive.

has:attachment size:>25mb

Putting it together: practical recipes

Goal	Query
Find big invoice attachments	`subject:invoice has:attachment size:>5mb`
All mail from two clients last quarter	`(from:acme OR from:globex) date:2025-04-01..2025-06-30`
Exact-phrase contract mentions	`body:"master service agreement"`
Newsletters to clean out	`from:newsletter -has:attachment`
Large messages from anyone	`size:>20mb`
A person’s mail, excluding receipts	`from:sam@ -subject:receipt`

Tips for faster searching

Start broad, then add operators to narrow results instead of retyping.
Combine search with export — filter first, then export the results to CSV or EML.
Use quotes whenever word order matters, especially for names and phrases.

Search any archive, instantly

These operators work the same whether your file is 5 MB or 50 GB. Open your MBOX and start searching.

Get Mbox Viewer on the Mac App Store →

Mbox Viewer Search Syntax Cheat Sheet