Workplaces increasingly use response speed as a proxy for hard work, signaling to employees that the only way to succeed is to be “always on.” Drawing on boundary theory and egocentrism, we examine a problematic bias around expectations of response speed for work emails, namely that receivers overestimate senders’ response speed expectations to non-urgent emails sent outside normative work hours (e.g., on the weekend). We label this phenomenon the email urgency bias and document it across eight pre-registered experimental studies (N = 4,004). This bias led to discrepancies in perceived stress of receiving emails, and was associated with lower subjective well-being via greater experienced stress. A small adjustment on the sender’s side alleviated the email urgency bias (a brief note senders can add in their emails to clarify their response expectations). This paper demonstrates the importance of perspective differences in email exchanges and the need to explicitly communicate non-urgent expectations.