For quick, general chat try Yahoo UK . There are a number of email address search tools. Most are referred to as White Pages after telephone books. There are also a number of Yellow Pages for business addresses. Further help Finding E-Mail Addresses of Individuals .
Many Universities provide search forms for finding a student's email address.
MMU does not. MMU Internal Telephone Directory . Most of the main search engines provide searching for a variety of specific things, eg. This is done either by forms or search syntax. Always consult the help pages.