On 17/07/2009, at 10:11 PM, Peter Funk wrote:
> Unfortunately currently the
> mailer class sends a message to all recipients at once.  Making the
> presence of the header dependent on the recipient would require to
> split the nosy list in two parts. :-(

The config "email_sending" variable already exists to control this  
behaviour. There's actually a bug filed about attachment handling in  
the split case.