You mean the private email Jason Knauf forwarded to a tabloid (not the tabloid his schoolmate edits, who he also leaked private emails to, a different tabloid) in order to attack Meghan, before William rewarded him with the top CEO job? The same Jason Knauf who was forced onto Meghan in order to spy on and leak nasty stories about her? The Jason who's the centre of all kinds of scandals and corruption allegations?
This is copy and pasted from the book itself: "We have spoken to close friends of Harry and Meghan, royal aides and palace staff (past and present), the charities and organisations they have built long-lasting relationships with and, when appropriate, the couple themselves." That is literally a direct quote from the book. (Omid clarified elsewhere that he has never interviewed either Harry or Meghan, merely briefly exchanged a few words.)
Can you provide a link to Omid testifying that he didn't speak to anyone on H&M's team, because why on earth would he say that when the actual book states that he did? (All I can find is him saying he never formally interviewed her, and that they didn't collaborate directly.)
The email is hardly a smoking gun, it doesn't show any direct contact between Omid and Meghan and only that Meghan provided some basic biographical details when asked. It does show that Jason Knauf pushed himself into the writing of the book, and given all the questions over his relationship with the Cambridges, Jason is the one who should be answering questions about his involvement and agenda in the book.