A courier travels to any mundane address the Priscus had for her family to deliver a thick, quality invitation size envelope. If she had only the Necropolis address, Jennifer hand delivered the invitation and went on her way.
The outer envelope was blank. Opening the thick envelope revealed the name that they went by, styled politely. For example " Mr. Alexander Moore'. This inner envelope was sealed with green wax and the Nosferatu family design was raised in the wax.

There was an invitation sized card within on fine vanilla colored cardstock.

Mr / Madame ( name),
I hope that this finds you well. I write to invite you to the family meeting on May 21st.
Attendance is mandatory, and so expect our cousins who do not live in the necropolis to be in attendance as well.
The meeting shall be in the Calidarium at ten PM.

Lady Notary Jennifer Hazelton, Priscus of the Nosferatu

There was a green wax seal and the family symbol pressed into the wax