My web app server sends emails. I also use Google Apps to host my emails. I can't send messages to my own users?

Please excuse the horrible title. I've been banging my head against this issue all afternoon, only to realize that I was on a wild goose chase.

In short:

Set up Google Apps to handle incoming emails for my domain (foobar.org)
Set up exim4 on my Linode to send outgoing emails for my web app
Tested by sending emails to my private email ([email protected]), and to work email ([email protected]).

After 3 hours, I still could not figure out why emails were being received at otherdomain.net, but not at foobar.org.

So I gave up. Ctrl+D out of the super-user account, and saw: You have new mail in /var/mail/julian

facepalm

So, any outgoing emails sent to foobar.org get delivered to the local user account. Makes sense. How do I tell exim4 to send the email out to the interwebs, so when it comes back to my DNS, it'll be routed to Google's servers?

Solution

In the end, I had an incorrect hosts file entry added when setting up my server.

I had the following entry:

public-ip    domain.tld    machinename

Although the following was more appropriate

public-ip    machinename.domain.tld    machinename

From then on, all emails sent to domain.tld ended up being sent out of the server.