-- Mention it politely.
As things return to normal, we're all beginning to contact one another about the boring things we must contact one another about -- bills, travel, figuring out where your new vacuum got sent after your local FedEx center turned into a large-scale aquarium, etc.
When contacting anyone in the Northeast, it's kind to include a brief reference to Sandy at the beginning or the end, e.g, "I hope you and yours are safe and dry after last week's storm." No need to ask for details or get too effusive in your well-wishing.
But ignoring the elephant in the room in your correspondence seems, well, a bit callous, especially since the storm may affect the recipient's ability to get back to you.
-- Tread lightly with work e-mails.
Similarly, when the wheels of commerce begin to spin again, offices will be back up and running at different dates.
A reader inquired about totally refraining from e-mailing people at work so as not to seem insensitive, which seems a bit extreme. If you're back on the job and have business e-mails to send, by all means, say what you need to say.
Just bear in mind that even if you don't get an auto-response, your intended recipient might not be working. If that's the case, follow up in a couple of weeks, when things are --- optimism ahoy! --- back to normal.