sending mail w/SMTP, domain probs

[many_pets]

I'm out of ideas here... hope someone can shed some light.
I have a php script that sends mail via SMTP (not sendmail or mail() ). Everything was fine... until.... I don't know what.
Now, apparently, I can send email only to addresses in the domain that the script is running in. E.g., sending email to a yahoo.com address, or an .edu address just doesn't work. But sending it to [e-mail] does work.

The site is hosted at ipowerweb.com. Could it be that something changed there? Or did I inadvertantly do something? What would cause this behavior?

Thanks.

[many_pets]

I should add that this is on a Linux system.

If I use mail() it works just fine to any address. (I don't want to use mail() because it overwrites the from: field and I can't trap bounced mail. Hence the move to the smtp server.)

Please... .ideas??

[many_pets]

Couldn't let it sit, Google to the rescue. Seems this is typical of smtp servers, where if you access without a password you are limited to where you can send mail. With a password, you can send anywhere.

And somehow, I messed up my access to the password in the db.

Hope this will help someone sometime...