jaredlwong

Posted: 05 May 2012

Gmail filters are powerful, yet most articles describing how to create powerful filters are not complete. This is my attempt at creating a near-complete guide to Gmail filters. (This is primarily based on my experiments using Gmail filters).

I owe a special thanks to this guy. Much of his experimentation is responsible for this guide.

Filter Maker

The filter maker is also known as the advanced search box. The drop-down arrow on the right side of the search box in Gmail will summon the filter maker. From the filter maker you can use any field to describe what you want to filter. However, the most universal field, and the field that I recommend using exclusively is the Has the words field. This field is a direct proxy to Gmail’s powerful filtering mechanism. At this point I recommend using a text editor to create, and save, your filters as you build them. (eg TextEdit, Notepad, TextMate, vim, emacs)

Filter Statements

There are two parts to every Gmail filter statement. The first part is the operator label (eg from:, to:, subject:). The second is the query. Filter statements are of the form operatorLabel:query.

Queries and Matching

Content that queries match against are expanded into words. Words are created by breaking the content at everything except letters, numbers, ampersands, and underscores. For example, someone@gmail.com is expanded into words equivalent to the list [someone, gmail, com].

Operator Labels

It is important to understand that each of the operators that act directly on emails (ie those that search some part of an email directly) simply isolate that part of an email and search it with your query. If the query matches that field then it will be included in your filter, unless negated by some other operator.

Main Operators

  • from: Searches the From: field of emails
  • to: Searches the To: field of emails
  • subject: Searches the Subject: field of emails
  • list: Searches the To: && From: field of emails
  • cc: Searches the Cc: field of emails
  • bcc: Searches the Bcc: field of emails

Potentially Useful Operators

  • deliveredto: Searches the Delivered-To: field of emails
  • label: Searches within a certain label you have created
  • has:attachment Searches emails with attachments
  • filename: Searches emails with attachment of this type
  • is:chat Searches gchat history

Time Operators

  • Format date as yyyy/mm/dd
  • after: Searches messages after a certain date
  • before: Searches messages before a certain date

In Operators

  • in:anywhere Searches all emails including trash and spam
  • in:inbox Searches emails in your inbox
  • in:trash Searches emails in your trash

Is Operators

  • is:important Searches emails marked important by Priority Inbox
  • is:starred Searches starred emails
  • is:unread Searches unread emails
  • in:read Searches read emails

Has Star Operators

  • has: Search emails with a type of star
  • Stars include yellow-star, red-star, orange-star, green-star, blue-star, purple-star, red-bang, orange-guillemet, yellow-bang, green-check, blue-info, purple-question.

Each of the searches in these fields adhere to the searching behavior as describedhere. They will not search in the trash or spam folders.

Boolean Operators

Officially supported by gmail: OR, -, ” ”

Other boolean Operators: AND, | ≡ OR, ! ≡ -

Expansion

Filter statements and queries will expand. Expansion happens with expansion operators. Note that operator labels cannot be expanded. For example, you can’t search the to and from fields by doing {to: from:}someone@gmail.com. You can do to:someone@gmail.com OR from:someone@gmail.com.

Expansion Operators

  • Statements without any parentheses or brackets are ANDed.
  • X Y ≡ X AND Y
  • Statements inside parentheses or square brackets, () or [] are ANDed.
  • (X Y Z) ≡ [X Y Z] ≡ X && Y && Z
  • Statements inside curly brackets are ORed.
  • {X Y Z} ≡ X || Y || Z
  • The pipe symbol | is equivalent to the OR operator.
  • X | Y ≡ X OR Y
  • The exclamation point ! is equivalent to the - operator.
  • X | Y ≡ X OR Y

Query Expansion Operators

Symbols in queries will expand.

  • ~#$%^*+;”,<>? act as AND operators
  • X~Y*Z ≡ X && Y && Z
  • -=\:’./ will wrap the words on the left and right in quotes
  • X.Y/Z ≡ “X Y Z” will match X-Y;Z (content is expanded on all symbols except letters, numbers, ampersands, and underscores).
  • ! can be inserted between words to negate them
  • X!Y ≡ X -Y
  • The @, ampersand symbol is stripped out at the beginning and end of a query. If in the middle of query will require absolute match of email mostly

Examples

This filter captures all email handled by student@college.edu. This filter will additionally capture anything to student@college.edu. This can easily be fixed but is usually sufficient.

(to:student OR from:student OR cc:student OR bcc:student) college

This filter captures all email to a particular student group if all of the emails of the group are of the form group-*@college.edu or related-*@college.edu. This works because content is split on almost everything, including a -.

(to:{group related} OR from:{group related} OR cc:{group related} OR bcc:{group related})
college

Sometimes I get spam from fellow students advertising their group’s event. On occasion they will only use bcc. This filter captures those emails that Gmail marks as having undisclosed recipients.

-to:{aero asia biz cat com coop edu gov info int jobs mil mobi museum name net org pro tel travel xxx}
-list:{aero asia biz cat com coop edu gov info int jobs mil mobi museum name net org pro tel travel xxx}

Occasionally I work on projects with other students. Say that their emails are person1@college.edu and person2@college.edu. And say that I only contact them by addressing both of them in the To: field. I can filter these messages like this:

to:person1~person2

I only prefer to use to:, from:, cc:, and bcc: explicitly in order to be sure that nothing will escape my filter.

Sources

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