I'm looking into ways to resolve this, but in the meantime:
Gmail appears to be throwing away more and more mail sent from the fiction@SH address.
If you've submitted using a Gmail address more than seven weeks ago [I originally said five here, but on further thought seven makes more sense, as we're a bit behind on responses], I recommend that you check your junk mail, and if there's no response there, then query immediately. If you have a non-Gmail email address where we can reach you, please provide us with that.
And if you've queried but haven't heard back from us, please check your junk mail, and if there's no response there, then please query again, ideally from a non-Gmail address.
And if you're about to submit to us, consider using a non-Gmail email address if possible.
Also, if you do find any SH correspondence in your junk mail, please mark it as non-spam, so that Gmail will have some evidence that mail from us isn't spam. (I'm not certain that will help, but it can't hurt.)
It's extremely frustrating. There's one author who we've sent about four responses to over the past three weeks, in response to queries, but apparently all of the mail we send her is being discarded by Gmail, so she's not receiving our responses.
I'm very unhappy about this whole situation. Will try to resolve it as quickly as possible, but we've responded to over two hundred submissions from Gmail addresses in the past two months, and I'm beginning to suspect that almost all of those responses have just disappeared into the ether.