This study aimed to investigate lexical bundles found in authentic English business emails and sample emails in business English textbooks to identify their similarities and differences. The data employed in this study were sample emails from 77 business English textbooks and those emails recruited from the Enron Corporation, representing authentic English business emails. The structural and functional categorizations of lexical bundles from Biber et al. (2004) and Biber (2006) were used as frameworks for the analysis. The findings show that structural types of lexical bundles in textbooks and in authentic emails were quite similar while functional types were significantly different. Although lexical bundles identified in both sets of data are centered around those in the Special functions category, which are associated with communicative acts such as request, expectation expression, offer, etc., a broader range of functional categories were featured in authentic business emails than business English textbook emails. Some implications regarding methodology and business email instruction, and suggestions for further studies are provided.