I've noticed that email forwarding to an address seems not to work if I send an email from the address to which I am forwarding email. This happens for GMail and Fasthosts mail servers. e.g I send an email to
firstname.lastname@example.org is set to forward to
email@example.com and the email never arrives.
I realise this seems logical but it is a potential cause of confusion when testing email functionality in a web application (for me, anyway ;-). I would just like to know if this is standard for all MTA software so I can avoid confusing myself.