Date: 14 Tamuz 5563
From: Rabbi Moshe Sofer
To: Rabbi Sender Meisels
An agunah's husband sent a get to Trieste, but due to the long distance and the woman's poverty, a local rabbi suggests sending the get via postal service to a local agent; the responsum discusses the halachic validity of this method.
Source: Shu"t Chasam Sofer CM §199