A method of low-redundancy e-mail handling, wherein: e-mail data is selected, attachments of e-mails comprised in the e- mail data are detached, stored and replaced with references accordingly, and wherein further e-mail threads comprised in the e-mail data are identified and split in separate e-mails, duplicates of e-mails are deleted while maintaining their e- mail references, differences between a first e-mail and an immediately preceding second e-mail of the same thread are identified, generating difference data, the first e-mail is replaced by the difference data, and a reference to the second e-mail is inserted therein, the e-mails and references to their predecessors and successors in the same thread are stored in a data storage, and a graph-based interface is generated for the stored e-mails and references, and an e-mail server computer device, e-mail client computer device, data processing program, computer program product, and computer data signal therefor.