I've searching for an agent since well before I found out about the postal rate increase. I've got several SASEs out still there with . . . gasp . . . insufficient postage. I'm finding conflicting information online about whether these letters would be delivered postage due, or returned back to the agent/sender. You don't have any in your slush pile, do you? What do you do with them?
Of course I don't have any in my slush pile. I answer query letters within about five days of receipt, and that's way up from my normal 24 hour turn around time.
Miss Snark harumphs mightily at the idea that a standard query letter has been out for more than a month, but not everyone is as brutally efficient as Killer Yapp the Query Letter Organizer.
For letters that are dated before 1/8 (ie when the postage went up) I put on the 2 cent stamp. Letters after that are cast to the munificence of the post office. Mostly I think the PO will process the mail but this is just a reminder to put your OWN return address on the envelope in both the TO and FROM positions.