eval {
  $dbh->begin();
  # stuff...
  $mime_entity_instance->send();
}
if ($@) {
  $dbh->rollback();
}
else {
  $dbh->commit();
}

##</code><code>##

#!/usr/bin/perl -w

use strict;

my $num = '123'; # an external database ID, for example
warn "(PID $$) Beginning transaction #$num ";
eval {
    my $pid = fork();
    if ($pid) {
        warn "\t(the parent does OK)";
    }
    else {
        warn "\t(the child fails)";
        die "Child process failure";
    }
};
if ($@) {
    warn "(PID $$) Rolling back transaction #$num: died in eval with $@";
}
else {
    warn "(PID $$) Committing transaction #$num";
}