But what does that mean, "not valid"? It's a valid address, used many
times, and I've tried it again to make sure it was entered correctly. Why
do these systems send error messages that can't be understood?

As an experiment, I made up a fictitious e-mail address and tried to send
it. I got the below error message, which is the same as what I got before,
except it says "PERMFAIL" instead of "TEMPFAIL."

The message could not be sent because one of the recipients was rejected by
the server. The rejected e-mail address was
'. Subject 'test', Account:
'ipostoffice.worldnet.att.net', Server: 'imailhost.worldnet.att.net',
Protocol: SMTP, Server Response: '550 [PERMFAIL] destination not valid
within DNS', Port: 465, Secure(SSL): Yes, Server Error: 550, Error Number:
0x800CCC79



"Poprivet" wrote in message
...
450 server error:
Requested mail action not taken: mailbox unavailable



This response is sent by the server to indicate that a message could not
be
addressed to a locally hosted recipient because the mailbox/mail address
is
not valid.
----------------------------

That's a generic statement really, indicating that the mailbox isn't
available for whatever reason. Could you be mis typing the addresses? Or
have them stored wrongly spelled someplace?

Also notice the "tempfail"; may be it's temporary thing. Maintenance,
whatever.

Just a thought,

Pop`





Larry wrote:
Using OE6 I was sending an e-mail to an address I've often sent to
before, using my AT&T Internet connection, and instead of the e-mail
being sent I got this message (I've changed the e-mail address to a
generic name with the same form and the subject to "Subject name"):

The message could not be sent because one of the recipients was
rejected by the server. The rejected e-mail address was
'. Subject '[Subject name]', Account:
'ipostoffice.worldnet.att.net', Server: 'imailhost.worldnet.att.net',
Protocol: SMTP, Server Response: '450 [TEMPFAIL] destination not
valid within DNS', Port: 465, Secure(SSL): Yes, Server Error: 450,
Error Number: 0x800CCC79

This happens from time to time: addresses I've successfully sent to
many times will suddenly cause this error message, and then at a
later point I can send to them again. It's not a permanent issue,
but it's very annoying when it happens.

What is the explanation for this?