TLS-RPT
Reports about TLS delivery failures between mail servers.
SMTP TLS Reporting lets domains receive aggregate reports when senders fail to deliver mail over TLS. It is commonly paired with MTA-STS so domain owners can see whether strict transport policies are causing failures.
reading this as early-stage startups
At an early stage the deciding factors are what the free tier actually covers, what the first paid invoice looks like, and how much of a founding engineer's week the setup costs. Feature depth that only matters at a million sends a month is noise until it is not.
Applied to tls-rpt, that means weighing free tier, best published rate per 1,000, entry price, and developer experience ahead of the rest, against a waitlist, a launch announcement, onboarding email, and the first transactional sends.