Hi abates1,

you have provided not that much technical details, so I need to be rather general in my response, sorry for that.

> We have an utgent issue with our External SMTP traffic, it all bounces with the code 553 (#5.7.1).
> Any idea on where to start the troubleshooting?

How about starting with the mail server that creates the 553 - if it's postfix on the SLES10 box, you ought to find more details listed in the logs of that machine.

553 is "relaying denied". In the thread title you talk about *outbound* emails - is this an initial setup our was this working before? Are there any new/changed configuration files on the reporting mail server? How have you set up your sender restrictions (user login, client machines per IP ranges/DNS names, sender email domain or anything else?

What mail server are you using? Could you tell us more about a specific (test) email - i.e. mail server logs for that test message?

With regards,
Jens