Formal Register and Email
Finland is one of the most informal cultures in Europe: nearly everyone — colleagues, bosses, even strangers — is addressed with the plain sinä (this is called sinuttelu). The formal te (teitittely) still survives with the very elderly, in official letters, and in polished customer service. The polite workplace register is really two things you already know — the plural te endings plus the conditional -isi- — stacked together.
Informal vs. formal address
Choose the polite form
Writing an email
Finnish email is famously brief and direct — no long flourishes. A typical structure runs greeting, opening, body, closing.
Say it yourself
Match the email phrase
Fertig?
Tipp auf den Button, wenn du alles oben durchgearbeitet hast — wir speichern es, damit es bereitsteht, sobald du dich anmeldest.