Any good webmail service should be able to send and receive mail from other accounts, thus allowing you to manage multiple email addresses (including work and personal accounts) under one roof. Gmail earns high marks in this area, offering support for both POP and IMAP. But Outlook.com supports only POP, so synchronizing mail accounts among multiple mail clients is much tougher. For example, the mail you read on your laptop wont sync with the mail you read on your smartphone, and vice versa. (The exception is if you connect via Microsofts Exchange ActiveSync; see Mobile access below.)
Thats a potential deal-breaker for some users, and arguably it's the only area where Outlook.com has a fundamental shortcoming compared with Gmail. For the former to compete, Microsoft needs to add IMAP support, stat.
Attachment handling and storage
When you receive a message containing, say, a Word file or PowerPoint presentation, opening that attachment should be a simple matter. Thankfully, both Gmail and Outlook make the task pretty darn simple.
I emailed a Word document to both my accounts. Outlook made a prominent show of the attachment, complete with a familiar-looking Word icon atop the body of the email. One click, and the document downloaded immediately in its native format (ready for viewing in Word proper), though I also had the choice of downloading it as a .zip file. Or, by clicking View online, I could view the document in Microsofts Word Web App, with the option of making quick edits right in my browser.
Gmail operated similarly, with simple View and Download options; the former steered me to a Google Docs viewer and, if I wanted, a full-blown editor.
As for attachment size, Gmail limits you to files no larger than 25MB, while Outlook.com caps them at 100MBor 300MB if you establish a link to your SkyDrive account. And speaking of storage, Gmail gives you just 10MB, while Microsoft promises an unlimited inbox. Granted, expanding your Gmail storage space doesnt cost much, but why pay if you dont have to?
Want to access your Gmail or Outlook.com account on your smartphone or tablet? With Gmail its a snap; Android devices have the service built into their DNA, and iOS devices list it prominently when you go to add a mail account.
With Outlook.com, things are a little trickier. iOS still has a button for Hotmail, not Outlook.com, on the list of compatible mail services. You can still use it to sign in to your account, but if you have a different top-level email address associated with your Microsoft account, thats what will appear when you try to compose a new message.