Filter rules get applied to messages upon sending or receiving. Each filter has a match condition and a list of ordered actions that are automatically applied server-side when the condition is met. Condition expressions yield a boolean result and are written much like in a programming language, with operators, function calls, the logical connectors AND, OR, NOT and parentheses. Typical actions consist of tagging the message, setting a priority, a status, redirecting or discarding it automatically.
The filter's direction can be Incoming mail to test the rule only against incoming messages (imported by manitou-mdx), Outgoing mail against messages that are written and sent with Manitou-Mail, Both for both incoming and outgoing, or None to disable the filter altogether.
The user interface has an editor for conditions and actions, launched by the menu command. Below is a screenshot with some sample rules defined:
Filter rule editor
The Filter field at the top right can be used to display only the rules that contain a given substring, either in their name or in their expression.