Learn Farsi: علی‌رغم دشواری زیاد، پستچی مرسوله را امروز تحویل داد. - Despite the great difficulty, the mail carrier delivered the parcel today.

You must use the ezâfe. Even though it is a preposition, علی‌رغم requires the ezâfe to link to the following noun or pronoun, making it alâ-raghm-e doshvâri-ye ziyâd. It works just like the phrase 'in spite of' in English, directly taking a noun phrase as its object.

Is مرسوله the usual everyday word for a package or parcel?

It is a formal, official word specifically used for postal items, dispatches, or mail. In everyday conversation, you would more likely hear بسته (package), but مرسوله fits perfectly with the slightly elevated, formal tone set by the preposition علی‌رغم.

Why is the time word امروز placed right before the verb instead of at the beginning of the main clause?

Adverbs of time are very flexible in Farsi. Placing امروز (today) right before the compound verb تحویل داد (delivered) puts a little extra emphasis on the timing. It highlights the accomplishment: despite the great difficulty, they managed to get it done today.

Where does the word علی‌رغم come from, and how is it formed?

It comes from Arabic, combining علی (alâ), meaning 'on' or 'against', and رغم (raghm), meaning 'compulsion' or 'spite'. In Farsi, it functions as a single prepositional unit meaning 'despite' and is pronounced as a single word.