I did the same in December, and sent 2 players some irons, one thanked me and uses them, the other no acknowledgement nor uses them. Doesn't bother me in the slightest as it is then their choice of what do do with them.
If it is in your account history as being sent, then they were received as you cannot decline. I assume they do not have a valid email to receive alerts so may be oblivious to the fact they have received the gift, or they do not want to use them.