Have posted about this before. Some threads here got me thinking about it again recently. Narrower choice these days. Hardware: iPhone 6, MBP, iPad. Wants: Push, read status syncing (ideal, but have been living without for a long time), seamless function; as close to complete reliability as possible; least likely to be "junked" silently by servers or to the junk folders of my recipients. Currently: iCloud for everything. Considering: Outlook.com for mail, and mail only; iCloud for everything else. Rarely use webmail interface, so split services not as big a deal. Would consider Gmail if there were a way to have push on iOS natively. Pluses with Outlook.com: push with read status synchronization; supposedly more reliable than iCloud, a biggie if true. Minuses with Outlook.com: split services just in principle; blacklisting issue (though seemingly not as big an issue as with iCloud). IMAP without IDLE, of unclear significance with Office 365 platform unification rumored; unclear if less reliable than Gmail. Would prefer one service for all but am trying to have the best of all worlds. Thoughts welcome. Like the idea of a custom domain and hosted service but contact field mapping and the little iCloud-specific things that can't be done with Exchange are an issue. Also don't want to bother with a custom domain.