Changelog
What shipped, newest first. Follow it with the RSS feed. An API version's breaking changes are in the API changelog.
Scheduling
Let your users be booked: hosts, weekly hours, Google, Microsoft and CalDAV calendars, and bookings with double-booking prevented by the database. Hosted pages are served at cossbook.com, with your branding on emails.
Support from the dashboard
Email support@coss.com or raise a ticket in the dashboard, with response targets per plan.
Forms
Hosted form endpoints for your site. Every submission is screened for spam, and accepted ones go to webhooks, notification emails and contacts.
Verify
One-time codes by SMS or email, with a fraud guard that stops SMS pumping before anything is sent.
Email for platforms
Sub-accounts give each of your users their own domains, suppressions, quotas and reputation.
Log drain presets
Send logs straight to Loki, Datadog or an OTLP collector, with an encrypted auth header.
Inboxes for AI agents
Give an agent its own email address, with received mail kept as threads and replies that thread in every mail client.
Phone checks in Risk
coss.risk.checkPhone() reports whether a number exists, its line type and its carrier.
SDKs for six more languages
Python, Go, Ruby, PHP, Java and .NET SDKs, generated from the OpenAPI document.
SMS
Send and receive text messages on the same key as email, with US carrier registration handled from one form.
Import from Resend, SendGrid and Postmark
Bring your domains, templates, contacts, suppressions and webhooks over from the dashboard.
Marketing email
Contacts, audiences, segments, topics and broadcasts, in a stream of their own so complaints never hold up password resets.
DMARC reports and dedicated IPs
Aggregate reports that guide a domain from p=none to reject, and dedicated IP pools as a paid add-on.
Integrations for Nodemailer, Better Auth and Auth.js
Send what your app already sends through coss.com without rewriting it.
SMTP relay and MCP server
smtp.coss.com for apps that can't call an API, and coss-mcp for coding agents.
Risk building blocks and rate limiting
Email and IP checks, content classification, device tokens, and a hosted rate limiter for your own endpoints.
Risk
Allow, review or block sign-ups, logins and other events, with the reasons why.
The coss SDK on npm, and sign-in with Google and GitHub
npm install coss, and a faster way into the dashboard.
Plans and pricing
A free plan, paid plans whose monthly fee becomes usage credit, and a public billing API.
Logs, log drains and directory sync
Environment logs and an organization audit log, streamed to your own endpoints, plus SCIM for your members.
Batch sends and dated API versions
Send up to 100 emails in one request, and upgrade API versions when you choose.