Hi Fordem,
Ok, thanks for that.  I realize pop3 is only for collecting mail, but it does make a difference as I only receive mail specifically addressed to one of my pop boxes, all other mail is rejected.  If I were using a system where by I received all mail sent to my domain I'd get the ones the DNS-323 is wrongly addressing to array-e-mail-alert@mydomain rather than the phill@mydomain.
You are correct, when I had the "sender address" set to anything other than one of the addresses of my pop3 boxes I received no mail alerts from the DNS-323 as they were rejected by my ISP and the DNS-323 test message shown mail faiure.  However, if I I set the sender address to my actual e-mail address I then get a failure message from my ISP and can see the incorrect addressing as being array-e-mail-alert@mydomain.
Interesting that you get correctly addressed alerts.  I'd have expected the same behaviour as I'm seeing if the coding is missing a closing bracket as posted by D-Link.  I guess there's more than one factor affecting this.
Cheers,
Phill.