Hi Amanda,
Brenda still has one posting on the board, that is why you get the message the inbox is full, when you tried to make contact. As mentioned by Berlin-Bob, in Reply #22 Brenda needs to make a couple of more postings, even if they are just smiley faces, to activate the Private Message system, then you can both send email addresses, as Brenda can't use the system yet.
Cheers
KHP