Is it Islamically permissible to deal and cooperate with American companies like Western Union for currency exchange from Euro to Moroccan Dirham?

If an amount is transferred in a specific currency and disbursed to the transferee in the same currency, there is no objection; because it is an agency for a fee. However, if it is stipulated that the amount be delivered in another currency, this is considered an agency and currency exchange (sarf), and it requires immediate possession (taqabud) in the same session. If this does not occur, the exchange becomes void, and the amount must be delivered in the same currency that was transferred. If both parties agree to exchange it for another currency, it is permissible at the rate of the day of delivery, based on the Hadith of Ibn Umar: "There is no harm in taking at its day's price, as long as you do not separate while there is still something between you."