You shouldn’t let anyone else create an email address for you. A lot of private information gets sent to your email address. Bank card information, password resets, confidential emails, etc.
If you make them for people then you’ll have access to that information also… You’re saying you’ll phone verify them, which means you’ll be able to reset the password after you’ve gave them over to your client. I don’t get why anyone would pay for this gig, it takes 1 minute to make an email for yourself. It sounds like a scam to me or a way of building a mailing list to sell on to people.