I have run a number of external DNS checks, and checked my RDNS entries and they all appear to be clean.
This is a new dedicated server in a datacenter - there was in issue with the IP address initially with one blacklist, but that has apparently been cleared up. I am not sure if this has any influence, but I doubt it.
In the case above, is the “to” domain located on your server?
There isn’t much of an error message there… however, one thing I’d suggest checking is to look at your hostname by running the command “hostname”… and then verify that your hostname is listed both in /etc/hosts, as well as on the mydestination line of /etc/postfix/main.cf.
I also can’t really see what the error message might be in your log, aside from the “bounced” status.
One way to get more information might be to turn on Postfix’s debug logging. To do so, go to Webmin’s Postfix module, icon Debugging features. There you enter 0.0.0.0/0 in the list of networks, and 2 for the logging level.
Then try to reproduce the problem you had, and /var/log/mail.log should contain a lot more data then. Please post that here, but enclose it in tags, otherwise it’s very hard to read.