Every email tool makes you pick a lane. Transactional (Resend, Postmark). Marketing (Mailchimp). Sales sequences (Salesloft). Three products, three data models, three bills — and your customer's reply lands in none of them.
I wrote that transaction boundaries live in the repository. Then a reader asked the question that broke it: one action, three tables, one unit of work. Where does the boundary live?
Say the pain, not the architecture. I described rootmail by its architecture: tenants, DKIM, reputation. And the reader still couldn't say what problem it solved. The pain is simpler: your customer's mail silently stops arriving and nobody can explain why. Lead with that.