It depends on what happens in your new() method. If you open up a connection to the outside world, then the mail server will be likely to be confused as multiple children babble. If the connection is opened in your initialisation_stuff(), then each object will start off as separate clones.

BTW your looping style is very C-ish. You will avoid most fencepost and off-by-one errors (both extremely common bugs) if you switch to the more Perlish:

foreach my $x (0..9) {
  ...
}
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