The first mail give you the feather. Since you're UC and above, the second mail gives you some uru so that you can skip tiers and start at 5 or 6 instead of 1. Don't try the SQ now, because apparently it's bugged
Why can I do the eq? It says it will only be available and the 7th.
You can do the event quest, but there is a bug in the side quest rn. So, don't do the side quest for now. You can check out the thread in bugs and known issues for more info
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