Please have a look at the attached output. A message is
to be sent to multiple recipients, one specified by -to
and one by -bcc.
As you can see, one address failes due to a relaying
denied error, but the final result of blat (set
errLvl=0) is 0, indicating no error.
I consider this to be a bug. blat shouldn't send the
email if one of the addresses fails.
To be compatible, I suggest to add a commandline switch
to reactivate the current behaviour.