Although I'm not certain, my guess is that this might be a grey user issue and the invalid emails are because their "From" emails aren't recognized and no Reply-To addres exists which would let them reply to the thread.

Evan's guess is probably true visa vie T4437 which shows a task being created via email then replied to via that creation email wit my personal @gmail which is associated with my account. Plus I poked around in the code...

@ahoffer - FYI / do you know if this is what is tripping up users? A fix would be to make sure they have registered the email addresses they are using to their Phabricator accounts.

We also do have the concept of gray accounts and need to make it better - see T1205 - so this should just work eventually (with emails not associated to any phabricator accounts) once we get that done.

@btrahan These users do have email addresses registered to their Phabricator accounts -- the issue happens to me, and I checked that my email is there on settings/panel/email/ . We're also using our Google Apps identities for Phabricator so it doesn't even seem possible that someone's email wouldn't be registered. I can reproduce this reliably so let me know if there's any other info I can get that would help.

@ahoffer - I don't suppose you can reproduce this on this instance of Phabricator? that would produce some helpful logs, and if they weren't helpful enough I could add some more debugging code to make them even more helpful (provided I can get you to reproduce again of course. :D )

I just tried T4447 - which was trying from a secondary email (i.e. "not primary") but that all seemed to work too.

(I can also take a look at this when we meet if we don't make progress before then.)

I haven't been able to reproduce it on this install but can repro it easily on our work installation :-/. I wonder if it might be a configuration issue somehow?

Ah, I figured it out. Or at least I found an old post by Euresti in which he figured it out, so it's basically the same thing. It is a configuration issue, namely that our install has messages come from <yourself>@dropbox.com and your install has them come from no-reply@phabricator.com. Gmail screws up the first case by stripping the reply-to field. I'll see about changing that setting, so I think we can mark this as resolved.

Sounds like people prefer not having messages come from noreply, but a practical workaround is to change your phabricator email to something like <username>+<string>@<domain> e.g. ahoffer+phabricator@dropbox.com. So that's what we're advising folks to do right now if this issue is annoying them.

See also @T600, which I think this is a duplicate of

Yeah, I think you're right.