Microsoft has completed migrating all Hotmail customers to Outlook.  The upgrade involved migrating 150 petabytes of email; which the Redmond giant pulled off in six weeks. Just how much is 150 petabytes? To give you a perspective, it would take 20 years to tweet 150 petabytes of data, if everyone in the world tweeted once a day.

If you are a Hotmail user, don’t worry; you do not need to change your email address or settings. Your Hotmail Plus account will continue to work with Outlook, as well. You may want to take a look at Microsoft’s FAQ page on the switch from Hotmail to Outlook.

Dick Craddock (Group Program Manager, Outlook.com): We want to give a huge ‘Thank you’ to all of you who have supported Hotmail over the years, for some of you, that’s going back as far as 1996.

There are now over 400 million active Outlook.com accounts, including 125 million that are accessing email, calendar and contacts on a mobile device using Exchange ActiveSync.

In another development, Microsoft is adding SMTP send to Outlook,letting users send mail from different email addresses.  Outlook is also getting deeper integration with SkyDrive.

Hotmail was one of the first Web-based emails, operated as a free service by Microsoft. Hotmail was founded by Sabeer Bhatia and Jack Smith, and acquired by Microsoft in 1997.

[Image courtesy: Microsoft]