2. Junk Mail
Messages arriving from outside Oxford are analysed by the Apache SpamAssassin Project. Only messages smaller than 512KB are processed by SpamAssassin. This is because the SpamAssassin scanning process is extremely resource-intensive and few junk mails are larger than this. The results of this are recorded in the message headers. Interpretation of this information is left for a downstream process. More details are available on mail scanning.