In what situations is Phabricator being sent messages it can not accept?

I tried to reply this via email, but email delivery failed
"""
Delivery to the following recipient failed permanently:

T5234+11341+2cefc59346ffe0e7@phabricator.com

Technical details of permanent failure:
The recipient server did not accept our requests to connect. Learn more at http://support.google.com/mail/bin/answer.py?answer=7720
[(10) smtp.phabricator.com. [50.18.110.231]:25: Connection refused]
"""

Thinking about it, I assume it's probably related to another change I made to not get "failure" replies when people reply in-line (because that's basically what everybody does). I basically just early exit, and I assume you added some way to tell that an incoming email was not handled at all (which it wouldn't have when it's an inline reply).

Generally, my use case is that I want phab to see as much of the email conversations as possible, but just ignore the stuff it doesn't understand; that way I can incrementally handle more cases from phab, without reconfiguring anything else.

(The permanent failure is unrelated -- configuration issue caused by an AWS restart that I've been too busy to sort out for the last couple of days.)

@epriestley - were you okay with this feature then? I'd envision a config option here-ish

https://secure.phabricator.com/config/group/metamta/

...and it would be like "disable sending error messages". I'd have the text warn against doing that though since I don't really think it should be happening? Seems valid if people are hacking on their Phabricator production though and don't want errors going to co-workers since they expect to be making a lot of them.

(If you don't want errors going to co-workers, don't hack on Phabricator in production -- even in this case, it's better for your co-worker to receive an error email than nothing.)

Ok, just tested replying to the email inline, and I get the following error:
"""Your email to Phabricator was not processed, because an error occurred while
trying to handle it:

Your message does not contain any body text or attachments, so Phabricator can
not do anything useful with it. Make sure comment text appears at the top of
your message: quoted replies, inline text, and signatures are discarded and
ignored."""
This is the reply I don't want to see.

In our case the others always already got the email via the mailing list (which is the primary system of reference for code reviews). If a mail can't be understood by phab, we don't care - phab is there to make list-based reviews easier, while getting in the way as little as possible.
Thus, every error mail somebody on the list gets when replying to a phab-based review on list is a distraction. 50% of our developers refuse to use phab, and want to stick to a simple email based review process, and we want to make it look to them as if phab doesn't even exist (even when the review is done with phab).