Translation:Shulchan Aruch/Orach Chaim/247

(1) A letter may be sent with a non-Jew even on the eve of Shabbat close to dark, [provided] he specified his wages and he doesn't tell him to travel on Shabbos and if he did not specify [wages], if there is not an established Ba'y Do'ar (meaning, a person about whom it is known to send letters to him and he delivers the letters to their addresses) in town, it is forbidden to send the letter even from Sunday and if there is an established Ba'y Do'ar in town, he may send it even on the eve of Shabbat, provided there is enough time remaining in the day that he is able to reach the house adjacent to the city wall. RAMA: There are those [authorities] who permit this even if he did not specify the wages and there is not an established Ba'y Do'ar in town provided he sends it on Thursday or prior to this and there is basis to rely on this if necessary.

(2) If he stipulated with him that he will give him wages, even though he didn’t say how much he’ll give him, the law is like they set a price, since the non-Jew is working for his sake. But if he didn’t mention it, even though his intention is that he’ll give him wages, it is forbidden since he isn’t depending on it and is working for the sake of the Jew.

(3) If he employs him daily, something fixed every day when he travels and when he returns, but he isn't particular with him regarding when he travels, if it’s the eve of Shabbat then it’s forbidden because it’s considered like Shabbat [and] it appears he stipulated with him about it.

(4) If the non-Jew carries the letter for free, even if he gave it to him on the eve of Shabbat, it is permitted because the non-Jew is only doing it to return favor because of what he receives from him [prior]. This is like they established a price. ''RAMA: There are some who disagree and maintain that anyone who does it for free is prohibited and it’s good to be stringent about this but in a place where the non-Jew takes the initiative with the Jew saying that he’ll travel for free, certainly his intention is on the benefit that he will receive from him and that’s permitted. (Beis Yosef)''

(5) If the non-Jew is traveling to another location on his own accord and a Jew gives him a letter [to take to that location], it is permitted in all cases.

(6) One who employs a non-Jew for the period of a year or more is forbidden from sending a letter with him on the eve of Shabbat. RAMA: However, if he is only employed for letter-carrying, there some who permit this, as established prior in Siman 244: 6.