I have a 7 year old solution that from the invoice layout (in one script) stores the recipient emails into a variable $eMail which looks correct in Data Viewer. It then saves a PDF of the invoice then uses Send Mail via E-mail Client; To: $eMail;......
The Emails in the 'To' section of the generated email were random emails from my address book!!!!
I have tested this in v12 on Maverick and v13 on Maverick and it went bad both times. Tested on v12 Snow Leopard was ok. It did not happen last month and I did not have Maverick then, just Lion.
This does not appear to happen with a single email, only Multiple email addresses (more than 3) and appears to be something to do with the comma separated characters so 3 or more commas.
I switched out the commas for semi-colons and FIXED!
This would have sent a client invoice to 5 different clients!