For i OS users, you can also drag towards the left to reveal a window which will show the time your message was delivered and subsequently read.
The drop-down menu offers the following options: All, None, Read, Unread, Starred and Unstarred.Finally, the Select drop-down menu offers quick selections of starred, unstarred, read and unread messages that you can subsequently delete. Click the "Delete" trashcan icon and confirm your selection, if prompted.Doing so moves all selected messages to the Trash folder, where are automatically deleted after 30 days; click "More," select "Trash," select all messages as you did previously, and then click "Delete Forever" to remove the messages immediately. Enter your filter criteria in the pop-up window -- for example, a sender's email address, a specific subject or a keyword. Enter "before:2013/09/30" in the "Has the Words" field and use the current date -- or any date, but make sure to use the format YYYY/MM/DD -- to filter all past emails. Click "Create Filter" to delete filtered results and return to the Filter list.Their findings: "I just got two tickets to Radiohead by being the 'first' to respond to a co-worker's 'first-come, first-serve' email.Someone else had already won them, but I told everyone to check their inboxes again.
Just click "Set custom time" from the Compose view.