opendir(MYDIR, $dirname);
while (condition) #condition ~ 1, loop basically forever
{
 my @mail = grep { $_ ne '.' and $_ ne '..' } readdir INDIR;
 foreach (@mail)
 {
  # do stuff
  # delete each file
 }
 undef(@mail);
 # @mail shuld be empty now
 sleep(1); # give cpu a break
}
# more stuff...
closedir(MYDIR);