Receiving moogle mail wedding invitations from strangers

Thread Title:
Several FC members & myself have received in-game Moogle Mail from people we do not have on our friendlist. Not sure how.

ISP:
AT&T Gigapower

Type of Internet Connection:
Fiber

Internet Connection Speed:
1GBps

Date & Time:
At our FC house in the Mist

Frequency:
One time

Character Name:
Araceli Sepharin

Race:
Hyur F

World:
Saragantas

Class/Level:
50 White Mage

Area and Coordinates:
Unsure

Party or Solo:
Solo

NPC Name:
None

Monster Name:
None

In-Game Time:
Unsure

Steps:
In-game mail was received around 1/4-1/5 timeframe - unsure the exact date, but was waiting to see if a friend name changed before reporting.
Received the invite from Ametarasu Sama for wedding on 1/11