Complaining constitutes a face-threatening and intricate speech act for native and non-native speakers of a language. Complaining implies reacting with discontentment to an act performed by the complainee, who is often urged to redress the predicament. In this context, pragmatic skills are vital because, unless endowed with an appropriate pragmatic repertoire and the corresponding language adequacy, speakers may jeopardize the communication process. Written complaints by non-native students have attracted scholarly attention in different contexts. However, written complaints by Spanish EFL students have been mostly neglected to date. Likewise, the influence of the writer’s gender on how complaints are performed has rendered some remarkable albeit scant studies. This study addresses the moves, strategies and substrategies deployed by Spanish EFL students in their emails of complaint, specifically looking into how the variable of gender influences their formulation of emails of complaint. For this purpose, emails of complaint of 90 L2 Spanish students with a certified C1 level were analyzed. Results show that students often transfer substrategies from their L1 and tend to delay the statement of the complaint in favor of lengthy openers, in contrast to native speakers. Furthermore, this preference for over-mitigation and over-politeness is especially employed by female students.