Often O365 (Office 365) can be misunderstood as it refers to some online offerings by Microsoft as well as the traditional Microsoft Office suite of products. So it can simply be a Microsoft Office suite product or an online offering of email (hosted exchange), that may include SharePoint online and the traditional Microsoft Office suite as well depending on the subscription taken out.
The online offering of Office 365 can be beneficial to business of all sizes as at the minimum you get is Exchange email which alleviates the need to backup your email which is imperative if you are on a pop3 type email service where traditionally only about 7 days of email are stored on the server. With an O365 hosted Exchange account if you have a hardware or software failure you can just setup your account on the new email profile in Outlook or access via OWA (Outlook Web Access) and have access to all your emails, contacts and calendars.
All your data is in the O365 cloud where Microsoft has a backup and redundancy implementation to keep your valuable data safe at all times with it backed up in geographically separate locations to minimise risk even in the event of a major disaster. Even if you use Hosted Exchange via other providers you need to make sure that their reliability, redundancy is good enough to trust your data with them. There are some excellent hosts that do provide Hosted Exchange however with Microsoft you will always be on the latest version of Exchange and or SharePoint and can have confidence that your data is in safe hands.
O365 also allows your company to have shared mailboxes and security groups. So for example your sales@yourcompany.com and support@yourcompany.com as well as any other email aliases you choose can have there own 10GB mailbox where you can specify which O365 users have access at no extra cost. The only exception here is any users on a “Kiosk” plan can’t access a shared mailbox. Users with permission can view and send emails from the address associated with the mailbox.
As you move up into the Enterprise subscriptions you now become eligible for extra enhancements such as IRM (Information Rights Management). IRM allows organisations to protect emails and documents at various levels. You can specify who can open, print, copy text and more both in Exchange and SharePoint document libraries. This is very easy to setup and provides you with controls to secure your companies valuable data including offline access.
Another enhancement is DLP (Data Loss Protection). DLP can help educate users without affecting mail flow and or enforce your company’s data policies. It can warn users when sending sensitive information such as credit card numbers and allow them to report false positives. It can also prevent emails being sent when in breach of company policy and is achieved through transport rules. Any activation of a rule can have an alert sent to specific personnel.
Also available in O365 is E-Discovery and In-Place-Hold. This allows organisations to search through all Mailboxes and SharePoint sites for data that meets specific requirements. Mailboxes can be placed on hold to prevent deletion knowingly or inadvertently. This can be done with or without the mailbox owner being aware and can be for an indefinite period.
Many organisations are now also moving there file storage to SharePoint online as it provides many options such as IRM, versioning access from anywhere. Employees are able to sync document libraries to there desktops. Storage limits are increasing as well as file size limits are increasing. One important point however is not all file types are allowed in SharePoint online. This technet link will provide you with a list of blocked file types as well as limits and storage however with the pace of change in Microsoft cloud offerings the information may not reflect new limits.