Learn Turkish: Postacı mektubu teslim etmek için geldi. - The postman came to deliver the letter.

You use the dictionary form (infinitive) of the verb, teslim etmek, followed by the postposition için. So, teslim etmek için translates to "in order to deliver" or simply "to deliver." This combination of an infinitive verb plus için is the standard way to express your purpose for doing an action in Turkish.

Why does the word for letter (mektup) have an -u at the end here?

The -u is the accusative case suffix, which is used to mark a specific direct object. Because the postman is delivering the letter (a specific one), rather than just a letter in general, we must attach this suffix to show it is the exact object receiving the action of the verb teslim etmek.

The dictionary word for letter is mektup. Why is it spelled with a "b" in mektubu?

This is due to a rule called consonant softening (or mutation). When a Turkish word ends in a hard consonant like p, ç, t, or k, and you add a suffix that starts with a vowel (like the accusative -u), those hard letters usually soften to b, c, d, or ğ. Therefore, the p in mektup changes to a b.

How does the ending on postacı work?