Is my SMTP password safe? I'm nervous about typing a mail password into another platform.

Snaptide states that SMTP passwords are encrypted and never exposed, which is the right answer on paper. The practical safety habits are yours though: use an app-specific password rather than your main account password where your provider supports it, and if you ever stop using the white-label email feature, revoke or change that password. Treat it like any stored credential — trust the encryption, but keep the blast radius small anyway.