Software giant Microsoft (MSFT 1.65%) announced today that it has completed its planned upgrade of its Hotmail email service as it transitions to its new Outlook.com email platform. Over the past six weeks, Microsoft has migrated 150 petabytes of data to the new service. Overall, the company said it now has 400 million active accounts using Outlook.com.

Microsoft is also adding new features to Outlook.com, including deeper integration with its SkyDrive cloud storage service. That will make it easier to send large attachments, among other added conveniences. SkyDrive integration will begin rollout out immediately, and will continue over the next few weeks worldwide. The company is also adding SMTP send, which allows users to send messages from other email addresses through Outlook.com.

The software maker also recently released a preview of Skype integration, which will bring the popular video calling service to Outlook.com.