On Wed, 12 Jul 2006 10:18:01 -0700, Enzo wrote:

Hi all,
I've been getting undeliverable mail messages every so often and was
wondering if the problem is on my end or the recipient's end. The error only
happens when I send to this certain recipient. The error is as follows:
Reason: Rejection greeting returned by server.
Diagnostic code: smtp;550 Too many invalid recipients
Remote system: dns;xxx.xxx.com (TCP|206.46.252.48|55273|162.115.227.108|25)
(Too many invalid recipients)
I am currently using Windows ME and OE6. Thanks for any feedback.

There can be two causes that I know of. The message relates to
"unauthorized relay". The causes that I can think of a

User error.
Server error.

User error is connecting to a network not recognized by the SMTP server
as an authorized source for relay. E.g.: My ISP is AT&T Yahoo! HSI. One
of the SMTP servers I can use is 'mail.pacbell.net'. If I connect using
my sister's Comcast connection, then attempt to send email through my
AT&T account, 'mail.pacbell.net' will recognize that it is not allowed
to relay for a Comcast connection, and send me the error. (I won't ever
get that error, though; AT&T Yahoo! HSI customers also have access to an
SMTP AUTH server which doesn't check the connecting IP address, just
that the user has an authroized login.)

Server error is an SMTP server incorrectly identifying a connection as
unauthorized. I recently add a new router to my network, which caused me
to rethink my IP numbering scheme. I changed the IP addresses on the
networked computers, but failed to update the IIS Virtual SMTP server on
a Windows MCE 2005 computer. It compared the new IP address with the old
configuration, and generated a 550 relaying error. I had to reconfigure
the IIS Virtual SMTP server to match the new IP numbering scheme.

The only other time I see a 550 error is when there is a list of RCPTs,
and either one of them is bad, or I hit the server limit for allowed
RCPTs. In either of those cases, as soon as MS Outlook Express receives
the server's 550 error, it aborts the send with an SMTP "QUIT" command.
The message is then not sent. In theory, MSOE could just stop sending
RCPTs, and move on to the DATA phase; but then MSOE would have to take
the responsibility to notify the sender of the failed receipts. I am
pretty sure that the coding for that would be complex; not something
MSFT would want to put into a client intended as a "giveaway" to users.

--
Norman
~Oh Lord, why have you come
~To Konnyu, with the Lion and the Drum