I am dispatching a few mails (mainly order confirmations) from a webshop using a php mail class. The mails are sent via a local Exchange/SMTP server.
In the majority of cases this works fine and customers receive HTML mails with PDF attachments. But in some cases customers complain about not receiving any mails at all.
MS Exchange informs about mails rejected by several servers - all with the same error message:
500 Line limit exceeded
Does the problem derive from my mails / mail class or is it a server setting? What can I do to avoid it?