I can't see anything wrong with line 29. It seems ok, according the Net::Cmd and Net::SMTP docs.

However, if you've added a couple lines since you got the error message you noted, I think it could be your statement in line 31-

close OUT;
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Two things-

1. Where do you open a filehandle called OUT? You can't close something you didn't open.
2. Did you mean to close STDERR instead? If so, you may want to close it after the loop, as the way you have it it would close it right after deleting the message.

Also, you should have the following lines at the beginning of your code. It will catch more errors -

#!/usr/bin/perl -w
use strict;
use warnings;
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(replace your current #!perl line with #!/usr/bin/perl -w)