Abstract: A method for determining e-mail address formatting rules corresponding to particular domain names, whereby e-mail address data is collected and sorted based on domains. Based on the gathered data for particular domains, a pattern is identified and an e-mail address formatting rule is determined. Format rule information is stored for future use to assist in correcting and directing e-mail messages so that they may be received by their intended recipients. Gathering of e-mail address data occurs by directly gathering e-mail addresses and e-mail address format data directly from entities responsible for the domain or format are derived based on patterns observed in collected address data for particular domains. Data for developing these patterns may be gathered from e-mail address information resident on the Internet, e-mail address information from e-mail address books, or from public e-mail address listings.