SMTP Relay Issue "550 5.7.1"

[ChicagoRookie]

Hi, Experts.

Is anyone give me an idea on this?
I have been having error message " 550 5.7.1 Unable to relay for for username@domainname.com".

for outside user, I setup outlook using pop3.
It seems to not authenticate when sending external domain.
interal domain is fine(internal domain1 to internal domain2)
I hosting couple domain for emails.

I also check smtp setting on ESM. As you know, We dont want relay open for exchange. if I take off limitation on relay option. emails are perfect(sending,receiving quickly). I know this mean security holes.(spam something)

I have spent whole week for this stupid error.
OWA is fine from anywhere.

So I narrow down this to Authentication issue on SMTP specially Relaying.

Any ideas would great appreciated.
Thanks



CCNA & NETWORK+
My every answer is
"There seems to be no pattern of when this problem occurs."
for Users..

 

[FilthPig]

The client (Outlook, Outlook Express, or whatever it is) must be configured to authenticate to the SMTP server.

For example: I only have an Outlook 2007 machine in front of me, but under the account settings, when you change it, you must look in the 'More Settings' area and configure authentication under the 'Outgoing Server' tab.

Most clients by default will make you use authentication information for the inbound POP3 but won't require you to set it up for outbound SMTP.

Marc Creviere

 

[ChicagoRookie]

Thanks for reply.
I actually did. It is not related to Client.
Changed setting on ESM, for authentication option, it did go thru.

but it still seems to have security hole. cause password sent in clear txt.

If someone sniff the network traffic, he can capture this.



CCNA & NETWORK+
My every answer is
"There seems to be no pattern of when this problem occurs."
for Users..