Add an indicator for incoming emails

Editor assessment

The subject states a concrete UI addition, an indicator for incoming emails, and chore is a doubtful type for a visible feature where feat fits better, though the straddle is arguable if the indicator was a missing affordance. No scope, no body explaining where the indicator appears or what it signals, unread email or delivery state, the semantics a user needs. No footers. The trailing pull-request number is conventional. Hygiene otherwise fine. Understandable, valid, miscast, and thin on the meaning.