All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
First of all, we ask Allaah to reward you for being keen on abiding by the Islamic Law and not acting before knowing the religious ruling about the matter.
In principle, the relationship between a man and a marriageable woman should be stopped in order to block the lures of the devil and to avoid one being tempted by the other. Therefore, you should not exchange these messages with him unless there is a religious need in which case there is no harm, provided this is done according to the necessity and within Islamic principles and morals.
It should be noted, however, that when a woman marries a man from another country, most of the time this leads to many disadvantages in the future. If this is the case, then you should first perform Istikhaarah (prayer for seeking guidance from Allaah when intending to undertake a given matter) and then seek the advice of a trustworthy religious person, and you should think twice before marrying, especially that your marriage to this man could be delayed because of his studies as you mentioned in your question.
Allaah Knows best.