Mail Transfer from InMotion to SiteJet

Hi, i need to transfer all of the emails of my client from inmotionhosting to sietjet, so whats the best way to do it? to create email i need to change MX records then i wont be able to access emails in inmotionhosting … any advise?

@mughal Check this article: In what order should I change DNS settings and use the Mail Transfer tool?