mass change upn and smtp addresss

we have 700 users, 200 of them are not happy with their smtp address. currently our naming convention is firstname.lastname@company.com , it will change to firstname@company.com .

1: smtp address will change to firstname only

2: login will change to firstname only

$bulk = modify-CSV 200_users_list_l1.csv
foreach ($_ in $bulk) {
set-mailbox -Alias $_.alias -UserPrincipalName $_.UserPrincipalName -primarysmtpaddress $_.newsmtpaddress}

will this work?