Google CEO Larry Page By Justin Sullivan/Getty Images The City of Boston has decided to rip out its Microsoft email technology and move 76,000 people to Google Apps.

These email accounts were previously mostly using Microsoft Exchange, according to a blog post by Boston CIO Bill Oates.

This is one of the largest customers that Google has swiped from Microsoft to date and is significant for a few reasons.

For one, it's another feather in Google's increasingly impressive cap. According to Google, Boston would be among the biggest contracts it has won for Apps. Other huge ones:

Microsoft isn't making it easy, though. In 2013, it announced lots of big contracts, too, such as a 100,000-seat deal with the State of Texas. Microsoft COO Kevin Turner even publicly bragged that Microsoft won back 430 customers from Google.

Still, Boston's CIO Bill Oates made it clear that Google's cloud won hands-down over Microsoft's when the city was evaluating both of them. In a blog post announcing why the city chose Google apps, Oats wrote:

In 2013, following an extensive review of the market, the city initiated a rigorous RFP process that attracted an wide array of bids, including multiple Microsoft and Google cloud offerings. A selection committee composed of members from our City IT organization, Boston Police, and Boston Public Schools evaluated 10 proposals based on both cost and technical capabilities. The committee unanimously chose Google Apps based on its ability to meet the needs of a fast moving city while providing a secure cloud environment.

The message is clear from Google to Microsoft: Game on!