Microsoft is preparing a new translation feature in Outlook Web and we will see it very soon. The feature is already available for Outlook apps on Windows and Mac, and will soon be coming to the web.

The Redmond company recently updated its Microsoft 365 roadmap page to include the entry “Translator for Outlook Web” which states.
In Outlook, you can translate words, phrases, and entire messages when you need them. You can also set Outlook to automatically translate the messages you receive into other languages. When you receive an email in another language, you'll see a message at the top of the message asking if you want Outlook to translate it into your preferred language.
Η Microsoft θα προσφέρει πολλούς τρόπους με τους οποίους οι users μπορούν να μεταφράσουν ένα email στο Outlook στο Web. Όπως η χρήση του εγγενούς μεταφραστή στο επάνω μέρος ή τη μετάφραση συγκεκριμένων λέξεων ή προτάσεων επιλέγοντας κείμενο στο email.
Microsoft says it will add a message at the top asking users if they want the email translated. It will also offer options to always translate an email or never translate emails. This way it will know your preferences in the future.
Once translated, Outlook will cache the data for 15 days so you don't have to translate it again.
The Microsoft 365 roadmap post says Microsoft plans to release the new feature in September 2023. However, it doesn't specify a date. So we expect the new feature to roll out gradually, until everyone sees it.

native translation coming soon. Let's hope that the translations made by outlook have correct Greek.
thanks for the correction