Not directly. We set up a dedicated (Gmail) account on our Google Apps service and have created several aliases for it in the Google Apps dashboard. So people are mailing in directly to it.
I’d think that the auto-forwarding would only work if the sender’s email address is preserved, and if it matches that of a valid user. If not, the mail would be rejected after Discourse polls the inbox. What do the forwarded messages look like in the inbox before Discourse goes to fetch them?
@democracy psyched to see you here too. 
We at Kabissa have been using discourse as a replacement our drupal/organic groups/og_mailinglist setup which was always half baked. Basically we’ve found that our discourse/google apps setup works much, much better! However, discourse forums are so different from mailing lists that we’re retraining ourselves to log into the site rather than hope that it will more fully replicate mailing list functionality. This is actually a Good Thing since it also creates more purposeful discussion over the long term and prevents everyone from being inundated with emails. But email still works very well to be notified and to give quick replies. Discourse is actually better than mailing lists with the ability to eg mention people to make sure they are notified, fork and move discussions, etc.
@downey thanks for the update on features and bugs - I haven’t looked at this closely for a month or two but am maintaining a (now out of date) list of mailing list functionality and their status over on the kabissa forum. If you or anyone else would find it useful to contribute to that topic I’d appreciate it.
Other features that I am missing that Steve and I discussed in the og_mailinglist issue queue two years ago (!!) are better membership management and import/export of both users and content. The stuff I prioritized there is still important to me, and I think with discourse we’re well on our way:
- improved presentation of discussion threads on the site including full support of file attachments
- MBOX import/export features to allow moving discussion archives to other platforms.
- CSV import/export features to allow migration of group members to/from other platforms
- improved membership lists/member directory for exploring and contacting fellow group members, seeing what they are posting, when logged in last etc
- improved membership management tools for group owners for inviting/adding/removing members
- improved error reporting and handling when e.g. email is bounced because of bad from address
Some progress is being made on these fronts:
The sender’s email address (as far as I can tell) is indeed preserved, however it just isn’t posting, even though I’ve told Discourse to allow unknown users to email in (which is something I do have working in individual categories at least.) That’s why I’m stumped. Perhaps it’s a bug then?
Hmm, could be. Beats me. 
I’m still in the process of getting ready to convince my organisation to switch to Discourse, so I haven’t explicitly tried this yet, but I believe muting categories achieves this objective - i.e. if they aren’t interested in a category, they mute it. Opt-out, as it were. I’ve just done a test on the prototype I’ve got running, so will see if that works or not.
Update: muting does suppress email notifications, so I guess that satisfies that requirement?
This is now implemented, closing