receiving an e-mail from an e-mail source;

identifying whether the e-mail has a vendor registration code for identifying a vendor from whom the e-mail was forwarded;

determining a source category of the e-mail by matching the e-mail source to an associated source category from a plurality of source categories, wherein each source category identifies related e-mail sources, the e-mail sources belonging to the same source category related to each other by a shared characteristic other than unwanted e-mail being delivered from the e-mail sources;

downloading from a database server the plurality of source categories associated with the e-mail sources;

when the e-mail has a vendor registration code that was previously assigned by a recipient to the e-mail source, presenting the e-mail with other e-mails received from sources having vendor registration codes; and

when the e-mail does not have a valid vendor registration code, presenting the e-mail grouped together with other e-mails determined to be in the same source category, adding information about vendor registration codes to the e-mail and returning the e-mail to the e-mail source;

wherein the information about the vendor registration codes includes instructions on how to register to obtain a vendor registration code.