Filter rules are not case-insensitive, meaning that the rules ignore capitalization.
Comparison fields include the following:
From. Use this to specify a name in the From: header of an email message.
To. Same as From, but looks for specified names in the To: header.
Cc. Same as From, but looks in the Cc: header.
To or Cc. Same as From, but looks in both To and Cc header.
Subject. Looks in the message's Subject header.
Header Named. When this option is selected, an additional text input field appears before the comparison operator (the "contains" portion). This option allows you to specify any email header. You can specify not only the standard fields of To: or From: but also Date, Reply-To, or other custom fields that may be included in the message header. You can use this option to filter out email messages that have "malformed" headers, meaning they do not contain certain information that is normally considered standard for an email message. Sometimes spam, which is automatically generated, omits information such as the Sender or Reply-To fields. Use the second text field (the field immediately to the right of the comparison operator) to specify the header to test for.
Size. Use this to select email messages that are larger or smaller than a specified size. The size of the email includes any file attachments. You can use this to discard email messages that are too large.
Date. Use this option to specify email messages sent before or after a specified date.
Body. The options for Body are Contains/Does not contain, and this allows you to specify matching words in the body of the email. You cannot filter for words in file attachments.
Is a read receipt. Read receipt messages can filtered.
Attachment. You can filter for email messages that have, or don't have, file attachments.
Address In. Tests for the presence of an address in your contacts. The next field allows you to specify which address.
Calendar Invite. You can filter calendar-related messages.
Comparison operators include the following:
Matches exactly/does not match exactly. Specifies an exact match. For example, specifying Subject matches exactly - Banana would only match "Banana" and not "Bananas" or "A truck full of banana leaves".
Contains/does not contain. Specifies that the subject line must contain the specified substring. For example, specifying Subject contains Banana would match "I'm going bananas".
Matches wildcard/does not match wildcard condition. The wildcard * is a character used in the mail filter comparison field to represent one or more characters in the filter. For example, specifying Subject matches " banana*" would match "bananas" or "banana-leaf casserole" but not "my banana-leaf casserole."
Keep in Inbox. Saves mail to Inbox. If none of the filter rules match an email message, this action takes place by default.
File into folder. Moves the mail to a specified folder.
Discard. Deletes the mail message without delivering it. The message is not in any of your folders, not even Trash.
Forward. Forwards mail to the address you specify.
Mark. Select as Read or as Flagged.
Tag with. You can tag matching messages with a selected tag.
You can create a filter rule made up of multiple actions. The combinations of actions in your rule are interpreted as follows:
Discard. If combined with other actions, discard is ignored and the other actions take place.
File into folder. Multiple "file into" actions results in multiple copies of the message being stored in different folders. If a specified folder does not exist, the message is saved to the Inbox.
Tag/Mark. These actions apply to the message returned from the nearest preceding action. In the case of multiple "File into" actions, this could result in some copies of the message stored without a tag, and others stored with a tag.
Keep in Inbox. Multiple "keep" actions can be specified, but only one copy of the message is saved to the Inbox.
Forward to address. Mail is forwarded to the address specified.