Ahh, thanks Ken! That definitely did the trick.
All 10 emails are now being sent, and all records updated accordingly. I have logged in with each of them and find them to be accurate passwords.
However, for any interested parties who comes across this in a search, please note that my use of:
$newpass = substr(uniqid(md5(time())), 0, 6);
is bad bad bad, as the password is being radomized against the time. And, as you know, all executions take place at the same moment, so the generated key will be the same for each. This is not good. Instead, I used:
$newpass = substr(uniqid(md5($name), true), 0, 6);
Which uses the username for reference, since it will be unique per every user/loop.
HOORAY! Works like a charm! Thanks for the help, guise!