Accordingly, users of the open email client can now turn on Do Not Track capabilities as a way to request that advertisers "leave them alone," in Bourcier's words.

"It's an option that you decide to turn On or Off, but we want to make sure this is your choice," she explained.

3. Ubuntu One Integration

Back in June Mozilla announced Thunderbird , a feature that lets you upload large files to an online storage service as well as sending links to your friends instead of large attachments. Now, in Thunderbird 15, such capabilities have been extended to Ubuntu One in addition to , expanding the options for fans of the feature.

4. Looks Like Firefox