Suggestion 1: Pay employees to monitor and instantly ban gil spammers.
Suggestion 2: Allow us to configure whispers to only be accepted by people on our friends list/within FC/both
Suggestion 3: No whisper privs until you gain level 10. Until then you're talking to yourself unless you're on their friends list. Alternatively, limit characters under level 10 to 1 whisper per minute.
Suggestion 4: Make blacklist useful. Adding a character should block that entire account. Right now the blacklist is absolutely pointless since the spammers just delete, re-create, and spam you again.
Suggestion 5: Add automation to catch and ban spammers.
Suggestion 6: Add an incremental delay after deleting characters before new characters can be created. First character is 30s. Second is 2m. 3rd is 5m. Do not allow new character creation on any server until this timer expires.

Suggestion 7: Do SOMETHING.