How about BB follow the sensible idea of many other online games and implement rolling Legacy Chat (basically showing conversation that occurred prior to the player logging in)
Whether it be 5 minutes of historic chat, the last 20 sentences or the entire day... surely it is time to start using this method.
How many players recently have got back to their game to find the [Please Refresh] button preventing them from seeing chat that happened while they were away.
Sit with TSO in the background for some hours and you will likely get forced refresh... Really annoying if you were waiting for response to a question in Help or Guild chat... Refresh as you are asked and you then have to ask the question again.
Though this feature might not be as useful in Trade Chat, I would suggest using it for all chat channels.
(maybe they could even include Legacy whispers and fix the old flashing-whisper-tab-bugsie)