Routing email into Slack, which is not the same as forwarding it

Every organisation that works in Slack still has email arriving somewhere else. Vendor notifications, form submissions, the address a partner replies to. The work is in one place and a meaningful slice of the information about it is in another, which someone checks when they remember. The obvious fix is forwarding. Point the mailbox at a Slack channel and let the integration post everything. It takes an afternoon, and it fails in a way that is worth describing precisely, because the failure is not "it did not work". It is that it worked exactly as specified and made things worse. What forwarding actually produces Truncated bodies. The integration posts a preview. The part of the email that says what to do is below the fold, so every message becomes a link to the thing you actually needed, and the channel is a table of contents for an inbox people are still opening. Reply chains, repeatedly. A thread with six replies does not arrive as one conversation. It arrives as six posts, each quoting all the previous ones, so the channel fills with the same text at increasing lengths. Auto-replies. Out-of-office, delivery receipts, no-reply confirmations. None of it is work and all of it arrives with the same weight as the message from a partner asking a real question. The predictable outcome is that the channel gets muted, and now the information is in two places neither of which anyone is reading. Routing, not forwarding The distinction that makes this work: a router decides what belongs in Slack and in what shape, rather than moving everything and hoping the reader filters. Concretely that means four things the forwarding integration does not do. Deduplication on the RFC Message-ID. Every email carries a globally unique Message-ID header, and replies carry In-Reply-To and References pointing back at what they answer. That is the correct identity for a message, rather than a hash of subject and sender, which collides on exactly the automated mail you receive most. The router