DB mail

Hi , need some assistance with DBmail , our ERP system uses a routine to create/send daily invoices to DBmail to then be emailed to customers . its become apparent that some of these invoices are being created by the routine but then not handed to DBmail , I don't have access to creation code but i can run a report on the email subject and see what's generated by one script is not being sent by DBmail . Friday 40 invoices where created but only 24 emailed . Does DB mail have a batch limit or is it most likely a problem with the Cursor inserting the emails for sending ?