NOTE: This question was originally asked about "Inbox by Gmail", when it existed, but Inbox has been retired and its Snooze feature rolled into Gmail. This question now applies to the Snoozed messages in Gmail.
Pending the shutdown of Mailbox from Dropbox, I'm exploring other apps that can offer the same kind of message postpone features. Gmail Inbox with Snooze is pretty close, except I also would like to access the "snoozed" emails via IMAP. (I'm writing the code, so it could be either IMAP or Gmail API.)
Is there a way to get the list of "snoozed" messages for Gmail Inbox programmatically?
Note that I'm not optimistic at this point, because this recent feature request for an email client requests the same thing, and the author (who probably knows more about the Gmail API than I do) says it's not possible:
Unfortunately, we can't support the categories in Google Inbox because they aren't exposed via the Gmail API or the Gmail IMAP interface. They're only available from Google Inbox itself.
I am also aware of How to find an email in Gmail that was snoozed in Google Inbox? which shows how to view snoozed emails from the traditional Gmail interface, but I can't seem to apply the same approach to IMAP.
Best Answer
Short answer
In your IMAP client try using search to find unread messages as "snooze" is not the same as any other Gmail feature.
Explanation
From How Inbox works with Gmail - Inbox by Gmail Help
Gmail's read later (mark as unread) is similar to Snooze but no the same. One of the main differences it that Snooze isn't implemented as a direct equivalent of an IMAP supported feature.