Time in transit.

Of 2 deliveries in the last 30 days, 100% reached the receiving server within five seconds of Postboi handing them to Amazon SES.

A provider gets its own row once it has taken 50 deliveries in the window. "All mail" counts every delivery, including companies on Google Workspace or Microsoft 365, which are filed under their own domains rather than as Gmail or Outlook.

1. 25 Sept: 100%

One mark per UTC day, oldest first. A red mark is a day with at least one minute missed.

• Delivery time is Amazon SES's own figure from its delivery event: the time from SES accepting the message to the receiving mail server accepting it. What happens inside the recipient's mailbox after that, such as spam filtering, is the provider's and isn't in the figure.
• Which provider is read from the recipient's domain when the event arrives. Only the provider is kept, never the address.
• Uptime is the share of minutes with a heartbeat. Once a minute a scheduled job runs the Worker that serves Postboi's API, which writes a row to the database. A minute with a row is a minute both answered. The job runs inside Cloudflare rather than calling in over the internet, so it measures the Worker and the database, not the network in front of them. A minute without one counts as down, even when the cause was the scheduler rather than us.
• Only mail sent through Postboi's own sending counts. Mail relayed through a customer's own provider, and sandboxed sends that never leave, are left out.
• The page recalculates every few minutes. Last measured 2026-09-25 20:47 UTC. The live check of each part of the service is on the status page.

Postboi's mail is delivered by Amazon SES in the EU (Stockholm, eu-north-1). Each team sends as its own SES tenant, so when a team's bounces or complaints run high, SES pauses that team and nobody else. Your own domain is signed with DKIM and gets its own return path, bounce. on your domain, so SPF and DMARC line up with the address you send from.

What we do to keep that reputation clean, from warm-up limits to nightly blocklist checks, is in the deliverability docs.