Poco Filter Modes

Filters can be run at various times in Poco. The filter window contains a number of tabs at the top that are used to group the messages under the various categories controlling when they run. To effectively use filters it is important to understand these categores: are:

The filters are run on messages after they have been read. The filter has access to the full message including the body.
Filters in the Outgoing group are run while the message is being transfered to the mail server. Such filters can manipulate the outgoing message including inserting text, changing options, etc. You should not use this type of filter to save messages in a mailbox because messages that are not successfully sent would still be filed in the mailbox.
These filters run on messages before they are downloaded from the server. Filters in this category only have access to the message headers (the body of the message has not been read). The main purpose of such filters is to deal with junk mail. For example I used to administer a website on a free server. The company that owned the server started releasing the email addresses from that server to spammers. I know have a filter on my incoming mail from that site and will delete any that is not directly addressed to me. Actions this type of filter can use are limited to those that act on messages on the server:
This type of filter is run after the message has been successfully sent. They are typically used to file messages in the appropriate mailbox. Any changes you make to the message using one of these filters will only be seen in your mailbox, the recipient(s) will not see the changes spawned by the filter. Any message that is acted on by an "Outgoing" filter where one of the actions of that filter is a terminal action will not be acted on by any "Post-Send" filter.
Various manual filter groups
Poco provides four other filter groups indicated by the numbered tabs at the top of the filter window. These tabs provide four manual categories for filters. Such filters are run by selecting one or more messages from the mailbox index and choosing the appropriate group from the "Run Filters Now" command on the "Tools" menu.