Approval mails sent to persons failed.

I tried the 6.x-1.9 version and revised a bug in this version (this maybe a bug).

When a new account created, I let a mail be sent to a role. While 3 more users are in this role, the mail have to be sent to many people. But it always complained for me. I checked the log file, and drupal said malformed mail address.

I googled and found http://www.daniweb.com/forums/post747190.html.
Then I added a comma ',' to divide the mail addresses and it works. I post here to make some people know this issue and thank the author and want to notify the author.