Official electronic letters, or formal e-mail messages, have become one of the most important forms of written communication in modern professional interaction. In such correspondence, terminological units play a central role because they ensure precision, brevity, logical organization, and genre-appropriate expression. This article examines the use of field-specific terminological units in official e-mail discourse across five major domains: business, education, law, diplomacy, and finance. The study shows that the lexical inventory of official correspondence differs depending on the communicative sphere and that each domain employs its own conventional terminology, formulaic expressions, and pragmatic patterns. The analysis also reveals an important contrast between English and Uzbek official electronic communication: English e-mails tend to be more concise, direct, and information-oriented, while Uzbek official e-mails often display a stronger tendency toward politeness, respect, and more detailed expression. At the same time, both languages rely on standard terminological and formulaic resources to maintain communicative efficiency and institutional correctness. The article concludes that the appropriate and norm-based use of terminological units enhances the communicative value of official e-mails and contributes to the standardization of professional written discourse.