Gmail filters guide

Gmail filters: rules, actions, examples, and the limits Gmail cannot cross.

Gmail filters are useful for known senders and repeatable patterns. KeepKnown handles the harder rule Gmail does not expose: sender not in contacts.

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KeepKnown screening unknown senders while Gmail filters handle known rules

What Gmail filters do well

Gmail filters turn search criteria into rules. You can match senders, recipients, subjects, words, attachments, dates, sizes, and categories, then choose actions for matching email.

Common Gmail filter actions

Apply a label.
Skip the Inbox and archive matching mail.
Mark mail as read or important.
Star, forward, delete, or keep mail out of spam.
Categorize messages as Primary, Social, Promotions, Updates, or Forums.
Apply the rule to existing matching conversations.

Useful Gmail filter examples

from:newsletter@example.com for one sender.
subject:"invoice" OR subject:"receipt" for billing mail.
{invoice receipt statement} for multiple related keywords.
has:attachment filename:pdf for PDF attachments.
category:promotions for Gmail category behavior.

The filter Gmail does not provide

Gmail filters require criteria you can name in advance. They do not include a native condition for every sender who is not in Google Contacts. That is the gap KeepKnown fills: known senders pass, unknown senders move to a recoverable KK:OUTSIDERS label, and nothing is deleted.

Source: Google Gmail filters help.

Short answer

Gmail filters are best for known rules, not unknown senders.

Use Gmail filters for senders, words, subjects, labels, attachments, dates, and category actions. Use KeepKnown when the rule depends on whether the sender is already in your contacts.

Choose the right next step.

Create a filter

Start with Gmail search options, test the criteria, then choose the actions for future matching mail.

Tune the action

Use labels, categories, Skip Inbox, Mark as important, or matching conversations for known patterns.

Screen outsiders

When the real rule is not in contacts, use KeepKnown to move unknown senders out of the inbox automatically.

Questions before you connect.

What are Gmail filters?

Gmail filters are rules that apply actions to messages matching search criteria such as sender, subject, words, attachment, size, date, label, or category.

Where are Gmail filter settings?

In Gmail on a computer, open Settings, choose See all settings, then use Filters and Blocked Addresses to edit, delete, import, or export filters.

Can Gmail filters apply to existing emails?

Yes. When creating a filter, select the option to apply it to matching conversations if you want the rule to affect existing email.

Can Gmail filters screen every unknown sender?

Not with a native not-in-contacts condition. Gmail filters need explicit criteria. KeepKnown adds contact-based screening for unknown senders.

Related inbox workflows

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