Email from Solaris to Exchange distribution groups

So yes, I need to send email, via mailx, from Solaris boxes, to Exchange distribution groups. Seemed like a better way than embedding a bunch of email addresses into my scripts. Seemed so simple. So wasn't.

I tested:

w | mailx -s "test to one email" me@mywork.com.au

And it works fine.

Then I created an Exchange distribtution group, with me as the sole member, and tested:

w | mailx -s "test to group" DST-Pinnacle_Backups-ROV@mywork.com.au

Didn't work. Why?

The trick turns out to be that Exchange distribution groups have, by default, a setting that requires senders to "authenticated" - this seems to mean "part of my Windows domain" - in that they have to be authenticated as Windows users. Clearly, sendmail on Solaris isn't going to to meet this criterion.

The solution: open properties for the distribution group, and click the "MailFlow Settings":

Then double-click "Message Delivery Restrictions":

Un-select "Require that all senders are authenticated". Simples!