Can't get SIEMENS SX56 to send POP3 email

The message I receive back from the siemens sx56 is "invalid recipients"  I
know they are correct.

Guys,

I've been through this and have at least temporarily solved the outbound
mail problem. (The "invalid recipient" error message is what I was getting,
too, BTW.)

I was told that the problem was that my outbound messages were being
rejected by my ISP as possible spam because it didn't recognize my wireless
device. I solved the problem by subscribing to SMTP.COM's hosting service.
You have to set Outlook to authenticate outbound messages. SMTP.COM charges
$50 for a year of up to 50 messages per day of outgoing mail. Disclaimer: I
am not connected with SMTP.COM, just a subscriber until AT&T figures out how
to provide hosting service as a part of their network (which they should
have done already, in my opinion).

Gary

For what it's worth I had the same error messages.
I tried setting the outbound smtp connection to use my local ISPs
server (they use Mailsite) with authentication turned on and it works
great now.
It seems that some SMTP servers will allow relaying from another
domain if you have an account and password!

It's been awhile since I setup SMTP anywhere (sendmail), and I don't
remember that being a feature. Maybe with the newer versions it is.
Steve

This makes sense.  Why didn't Siemen or AT&T tell me this when I called them
on 3 separate occasions.  And spent over 3 hours with them on the phone in
wait time to be told that it was Siemens problem, AT&T's problem, my
problem...  etc.!

Thanks Gary!