Make sure that you check junk/spam, and on gmail, check the “promotions” tab, I found mine in there.
Thanks! Fingers crossed!
Going to close this off due to to the volume of similar threads about invites between here and the Insider forums. Please see my pinned PSA for more information
https://www.halowaypoint.com/en-us/forums/243780d3b80b4bb6ac7917a8942286db/topics/psa-infinite-technical-preview-flighting-emails/6c6dd04a-e2d7-4659-bafa-ac6822ec6153/posts