Send your first email
Create a scoped key, verify your sending domain and follow the API request through to its resulting status.
Open the quickstartSetup and troubleshooting
Find your next step
Get SendMailOS setup and troubleshooting guidance for domains, API, SMTP, webhooks, reply capture, Template Studio and own-server sending.
Start with the task in front of you
Connect your own server
Check provider restrictions, prepare your VPS, connect it to SendMailOS and review its sending route.
Server setup guideUnderstand plans and costs
See your platform subscription, included hosted allowance and separate VPS estimate. Subscriber and server limits also determine the plan you need.
Plans and calculatorTroubleshoot the next step
Domain verification is pending
Compare each DNS name and value with the dashboard. Publish records at the displayed hostname and run the verification check again after your DNS changes are available.
Domain and API setupA message is queued or failed
Keep the message ID and request ID. Check the current status, response error and retryable flag before creating another send.
Responses and errorsSMTP is not connecting
Check the documented hostname, port, encryption and authentication settings. SMTP submission and a VPS sending directly to recipient mail servers have different network requirements.
SMTP setupWebhook events are missing
New endpoints remain inactive until they pass the signed verification challenge. Confirm signature handling and the exact challenge response, then inspect delivery attempts.
Webhook setup and retriesReplies are not in Inbox
Review receiving setup and the Reply-To used by the original message. Enabling capture applies to future supported sends; older messages keep their original Reply-To.
Inbox setup overviewTemplate Studio cannot see a workspace
Check which organizations and permissions you approved. Manage the connection in Connected Apps; reconnect to approve additional organizations when needed.
Template Studio connectionKeep a useful troubleshooting record
Include the context, protect the credentials
Record the feature, UTC time, request or message ID, exact error code and the steps that led to it. Remove API keys, passwords, OAuth tokens and recipient content before sharing screenshots or logs.
For repeated sends, preserve the same idempotency key for the same intended operation. A fresh key may represent a new send.
Questions, answered
Does queued mean my email was delivered?
No. Queued means the platform accepted the message for processing. Check the message status or a delivery event to see what happened next. A delivery event still does not guarantee inbox placement.
Can I test the API without sending real email?
Yes. The dashboard can issue TEST_KEY_ credentials for simulated email sends. Test keys do not deliver messages to real mailboxes, and their write permissions are limited.
Why did reply capture not change an older email?
Enabling reply capture affects future supported sends. Messages already sent retain the Reply-To address they had at the time.
Should I retry an API request immediately after every error?
No. Read the response error code and retryable flag. Keep the same idempotency key when retrying the same intended send and follow the responses-and-errors and idempotency guides.