Bridging the Gap Between Slack and Email Users

This post details the architecture and implementation of the 'Email Bridge' feature, which bridges the gap between Slack and email users. It introduces the concept of 'Invited members' with a specific flag to indicate unaccepted invitations, making them visible in search and for @mentions. The core of the feature is the 'Email interoperability service' which batches messages into emails for invited users and routes their email replies back to the appropriate Slack channel using a unique Reply-To address and AWS SES/SNS. The post also discusses lessons learned from expanding the feature to Enterprise Grid, the importance of instrumentation, and the strategy of shipping a proof-of-concept quickly and then refactoring.