multiple recipients windows live mail

I regularly need to send emails to multiple recipients in a group email. Mostly this works fine but there are some recipients who do not receive these emails although they receive individual emails from me. Does Windows Live Mail have a limit on the number of recipients in a group or the total number of emails which can be sent?

Second question: Is there any way of getting an automatic report back  when a particular recipient does not receive one of the emails?

Thanks

Colin, Rugby