BlueMail is an email client that lets you access all your inboxes with a single app. It's compatible with countless email services, so there's no need to worry about compatibility.
Compatible services include Gmail, Yahoo, Office 365, AOL, Google Apps, Hotmail, Outlook, 1and1, iCloud, UO Zoho, GMX, IMAP, POP3, and Exchange. You can access several inboxes or combine them into one.
Its avatar-based interface makes it easier to navigate your inbox, favorite certain messages, and search for contacts with autocomplete. Give it a try! What do you have to lose?