Using POPFile's toptoo option

Here are some situations where mail clients typically use the TOP command:

Note: Setting toptoo to true (1) will mean that every message appears twice in your Popfile History. This will have only a nominal impact though, because the history gets cleared automatically after a few days and overall accuracy should be the same. Either message can be used to reclassify the message within POPFile.

Using a POP server in an "IMAP'ish" style

Some mail clients act in an IMAP'ish manner in the sense that they leave all mail on the server, use TOP to grab the headers, then use TOP whenever the user wants to view a message in the mail client. These clients can pull a particular piece of mail from the server multiple times since they treat the mail server as the primary message store and continually go back to it to grab copies of the message.

For clients that work this way, toptoo MUST be enabled or else the client would NEVER receive classified mail.

Note: In this usage model, POPFile is only helpful in removing SPAM and leaving “ham” (good email). More complex tasks like sorting email into folders aren't possible because each time the user polls the server they will get the same email again, and reclassify it, but mail won't be moved into any folders.


There are several mail tools such as POPTray and Trillian that permit one to 'preview' mail on the server, and in some cases, filter it based on the header information. For example, it could notify the user when mail from a manager or spouse arrives. They use the TOP command to grab those headers.

For tools like this, it can be very desirable to have toptoo enabled so the message classification is available to the filter (or human) making the decision to delete mail on the server.

Note: POPFile had to retrieve the entire message to classify it, so no bandwidth savings is taking place here and the message will be downloaded a second time by the email client used for viewing, storing, and sending email (unless the message was deleted by the “preview” email client).

This usage makes the most sense when the “Preview” offers something the chosen email client doesn't. Otherwise, the user is just introducing more bandwidth burden, CPU burden, and configuration complexity than just allowing the mail client to do this work because every email will be downloaded and classified twice.

Skipping messages larger than a certain size

Most mail clients have an option buried somewhere in the account settings that let the user limit the size of a piece of mail that will be downloaded. Typically, those clients will do so using the TOP command, which enables them to specify the number of lines of the message to download. Again, in those cases, the TOP would be proxied to the mail server by POPFile and the 'short message' returned would NOT be classified unless the user had toptoo enabled.

Note: An example in this case might be a user who is on the road at times, and therefore wants to download only headers or only email smaller than X bytes…POPFile could classify and deal with spam (which is often small) AND any of the other messages that are small enough to be downloaded, while leaving really big email on the server.

See also:

howtos/toptoo.txt · Last modified: 2008/02/15 17:47 by

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