I have 2 suggestions to minimize this annoyance:

1 - Basic Feature: Whitelist

Today you can block /tell messages by setting your status to /busy, but it do not allow you to participate on ready checks and receive tells and invites from friends and company members.

My suggestion is a new status (or simply a checkbox on somewhere) that will block /tell and friend requests from any player that is not on your:
  • Friend List
  • Free Company
  • Linkshells


2 - Advanced Feature: Spam Filters

Use regular expressions to filter messages you receive.

Example:

when you place this filter:

Code:
0{3,4}\s?[kK]
The following message will be blocked and never will be displayed on your client:

"Buy Gil 1000K = $10."

A message filter like this is already possible by using 3rd party software, but it violates the TOS from the game, so would be very nice if you allow us to do it directly from the game user interface.