Two changes you'll spot the first time you use Mail in iOS 6 are a couple new entries in the top-level Mailboxes list: VIP and Flagged. These mailboxes are similar to Smart Mailboxes in OS X Mail, in that each gathers particular messages across all your inboxes and presents those messages in one convenient list.
The Flagged mailbox displays any flagged message--those you've marked with Mail's flag feature (more on that below)--located in any of your mail-account inboxes. (It doesn't show flagged messages you've filed into other mailboxes.) This is a feature people have been asking for since flagging debuted in iOS 5, and it makes it easy to quickly see your most-important messages without having to scroll through all the other messages in your inboxes.
The VIP mailbox, which debuted in OS X Mail in Mountain Lion, gathers messages from people you've designated as VIPs--your spouse, your boss, your bookie...er...financial advisor--so you won't overlook those messages in the daily flood of email. (Unlike OS X Mail's VIP feature, which shows VIP messages across all mailboxes, iOS's VIP mailbox shows only messages located in your inboxes.) And perhaps the best part of this feature is that it syncs using iCloud, so if you add a VIP on your Mac, it's automatically a VIP on your iPhone and iPad, and vice versa.
To designate someone as a VIP, tap the blue-and-white arrow at the right edge of the VIP item (in All Mailboxes), then tap Add VIP and choose the person in your contacts list. (The person must already be in your contacts list to add them as a VIP.) The VIP List screen also shows your full VIP list; to delete someone from the list, either right-swipe across the contact's name or tap Edit.
The other item of interest here is VIP Alerts. Tap this button, and you're taken to Settings -> Notifications -> Mail -> VIP, where you can configure iOS-notification settings for email received from VIPs.
In iOS 5, your notifications options for Mail (found in Settings -> Notifications -> Mail) were much like those for any other app: You got one set of notification settings that covered all incoming email. In iOS 6, you now get per-account notification settings, as well as separate options for VIP messages.
Go to the Mail screen of Notifications settings and you see three sets of options. The Show item simply lets you choose how many unread email messages appear in Notification Center. The other two groups are where you fine-tune your notifications.
Choose any email account from the list, or the VIP item, and you get--for each account or for VIPs--the standard Notification Center options: alert style, app-icon badge, whether or not to show a preview of the message, or whether or not to view notifications on your device's lock screen. In other words, you can choose to enable all options for your work account, but only some for your personal account.
The other new option here is the capability to choose a different alert sound for each email account, as well as for VIP messages. Which means there are now three places you can choose sound alerts for new email messages:
For years, emailing an image or video you've taken on your phone has been counter-intuitive: you had to open the Photos app, choose the item(s) you want to send, and then create an email message, with those items attached, from within the Photos app.
Not anymore. In iOS 6, you can finally add photos and videos to email messages the way every other email client does it: from within an email message. However, the procedure isn't immediately obvious.
When composing a message, tap-hold or double-tap in an empty area of the message, and in the popover that appears, tap the right-facing arrow. Tap Insert Photo Or Video and a Photos-app-like media browser appears. Choose an album, and then tap any image or video in that album to view a preview. If you like what you see, tap Choose to add the image or video as an attachment. Repeat the process for each additional item you want to attach. (I've successfully added 12 images to a single message; I haven't yet discovered if there's a limit.)
When you tap send, you'll see a screen that tells you how big the current message is and asks you if you want to scale your images down to reduce the size of the message. Just tap the desired option (Small, Medium, Large, Actual Size, or Cancel).
One of the most welcome improvements to Mail is that you can now configure a different signature for each of your email accounts. Go to Settings -> Mail, Contacts, Calendars -> Signatures, and then choose Per Account. This enables a separate signature field for each email account you've set up on your device. Type or paste your preferred signatures, and Mail will automatically append, to each outgoing email message, the appropriate signature for the sending account.
You no longer force Mail to check for new messages by tapping a clearly visible refresh button at the bottom of the screen. Instead, Apple has in iOS 6 adopted the trendy "pull to refresh" approach first found in the original Tweetie Twitter client for iOS. This means that when you want to force an email check, you must first navigate to a mailbox view or the Mailboxes screen--you can't force a refresh while viewing a message, as you could in iOS 5. Then you swipe the screen downward as if you were trying to access the Search field while in a mailbox. Once you see a little refresh button (the one with the circular arrow) at the top of the screen, keep swiping until that button stretches down and then "snaps back" to a progress indicator.
(As in earlier versions of iOS, Mail automatically checks for new messages whenever you open the Mail app and whenever you open a mailbox.)
Some of our favorite new Mail features are the kinds of little things you could easily miss. For example, if you tap-hold Mail's new-message button, you get a convenient screen for choosing one of your saved drafts; tap a message to continue working on it, or tap New Message to start a brand-new message.
When viewing a message, it's now easier to mark it as unread, and to apply or remove a flag, thanks to a dedicated Flag button in the toolbar at the bottom (on an iPhone or iPod touch) or top (on an iPad) of the screen. In iOS 5, this functionality was hidden behind a Mark link located in the message headers--and that link was itself hidden unless you'd chosen to view the full header details.
Speaking of headers, another minor useful tweak is that you can now see--in small, gray characters--the recipients of a message, even if you've chosen to hide header details. In addition to being helpful when viewing sent messages, this is also useful for incoming messages by letting you see whether you were the primary recipient or a CC or BCC recipient.
If you and the people you communicate with are fond of top-quoting (a.k.a., bottom-posting), where quoted material is placed at the top of the message and your reply is placed at the bottom, iOS 6 Mail helpfully collapses, accordion-style, much of the top-quoted text, making it easy to read the latest lines.
Finally, if you've got an email account that supports message archiving (Gmail, for example), you can now choose, on the fly, whether to archive or delete a message. While viewing a message, tap-hold the Delete button, and you'll get a popover menu listing options to Delete Message or Archive Message. Just tap your preference for this particular message.
Despite its long evolution, Mail still lacks some features you might like in an email client. Among the lingering gaps:
The good news is that with iOS 6, these remaining major feature requests feel more like gravy than meat: Though it still has limitations, Mail feels more like a full-featured email client. As I said of Mail in iOS 4, the app gets most of the basics right, and it excels at the most important tasks: viewing and composing messages, displaying attachments, and connecting reliably to nearly any e-mail server. In the two years since that statement, Mail has matured significantly, to the point where even power users can be satisfied.