SMTP
Classic host / port / login / password for apps that cannot call the API
Connection
Fill these plus a mailbox username and password in WordPress, GitLab, Proxmox, Home Assistant, or any app that only speaks SMTP. Mail goes through the same quotas, DKIM, bounce handling, and stats as API sends.
No SMTP mailboxes
Create a mailbox on a verified domain to get host, port, username, and password for self-hosted apps.