so i could e-mail my family and friends back home for free
整句话的意思是：所以我可以免费写电子邮件回家给我的家人和朋友.
但写得有些像中国人英语.
这样或者会好些
So i could e-mail back to my hometown to my family and friends for free.
所有我可以免费写电邮回我的家乡给我的家人和我的朋友.
So i could e-mail my family and friends for free.
意思是：所以我可以免费写电子邮件给我的家人和朋友.
back home 回家的意思.