Mailbox for iPhone lets you send each email to a list, set it to snooze for a certain number of hours or days, or even just archive the email if you want.
In addition, you can mark emails as read or unread, and star them, just like in Gmail itself. THis gives you yet another way to sort and classify emails on the go, which also transfers easily to the web version of Gmail, as well.
WHile in Mailbox, tap on an email or an email conversation. When it’s a single email, hit the little disclosure arrow to the right of the date, and tap on the blue bubble there. This will mark the email Unread. Tap it again to mark it Read.
If you have several emails threaded into a conversation, you’ll be able to just tap the date to the upper right of the specific conversation email, and it will turn blue. This marks that specific email as Unread as well. You can mark it Read with a second tap here, also.
To star an email, you’ll need to be in single email view. If you’re in conversation view, tap the email subject once to open it as a single message. Then you can Star the email with a tap on the little white star to the right of the subject line, turning it yellow. I use stars to easily find important email that I Archive.