Subspace radio marriage
From Memory Alpha, the free Star Trek reference.
In the late 23rd century, the subspace radio marriage was a means of marrying someone when more conventional methods weren't available.
In 2266, lithium miners Herm Gossett and Benton married Ruth Bonaventure and Magda Kovacs using this method. Such a marriage could be negated in the event of fraud, as when the miners discovered that these women were enhancing their beauty with the Venus drug. (TOS: "Mudd's Women")
