A welcome email is most useful when it helps someone continue a task they have just started. It should arrive because an account was created successfully, not because a signup form was opened or a page was refreshed. That small distinction shapes both your code and the message.
Trigger from committed application state
Create the account first, then record the welcome-email event. If signup is rolled back, there should be no welcome for an account that does not exist. Give the event a stable ID and store the resulting Sendar message reference with it.
Do not trigger the same welcome from both the signup handler and a generic login callback. Social sign-in flows can make that duplication easy to miss. Test first-time registration separately from returning-user login.
Give the message one useful job
Choose the next action a new user needs to take: complete a project, connect a domain or open their first workspace. Explain that action in plain language and link to a stable application route. A long list of unrelated features is less helpful than a clear continuation of the user's task.
Keep a verification email separate when verification has its own token, expiry and authorisation requirements. A welcome message is not proof that the recipient's address has been verified.
Keep personalisation resilient
Decide what the message should say when a name is absent. Escape user-provided values before including them in HTML. Use realistic long names and non-Latin characters in previews rather than testing only a short example.
A saved Sendar template can keep wording consistent across application code paths. Check the expected variables before changing the template, because a content edit can affect an integration that already depends on those names.
Measure the action after the email
Record whether new users complete the intended onboarding step in the product. Email engagement alone cannot establish that onboarding worked. If many users stop before sending their first message or finishing setup, investigate that step rather than assuming a more enthusiastic welcome subject will fix it. Use the email to support a working product journey.