That seems like an awfully cumbersome, uncharacteristically Apple way to accomplish a task that many people probably do several, if not numerous, times daily.
There's really no other way to partially delete the contents of a mailbox?
I was responding to Slolerner's specific situation where there were hundreds(?) of messages to be deleted and a relative few to be saved and was not intended to be a comprehensive tutorial covering all possible situations.
If one is cleaning out the mailboxes daily or hourly you can individually select the messages to be deleted and then press Delete.
IF you had, and regularly used, an iOS device running iOS 8 or later you would be more likely to understand that although iOS and OS X both run on the Darwin kernel their different operating environments, I/O tools,
etc impose significant logical, and very reasonable, differences between two platforms. If you seriously want to learn more about iOS watch for the forthcoming release of
iPhone: The Missing Manual, 9th Edition.
