Apple has launched an update to iOS 11, a week after the software was officially released on September 19. The iOS 11.0.1 update fixes a serious bug that prevents users from sending emails using Microsoft-hosted accounts in Outlook.com. An Exchange Server 2016 running on Office 365, or Windows Server 2016.

After updating to iOS 11, many users see an error message – “Mail cannot be sent. The message was rejected by the server” – when trying to send an email using a Microsoft email account.

Apple has announced an update on its support page, but the update isn’t yet available on all iOS devices. This could be because Apple is rolling it out periodically. To check if you have received the update, go Check for settings, general, software updates and updates.

For those who are still on iOS 10, reports suggest that iOS 11 drives battery life on iPhones and iPads twice as fast as its predecessor. However, the software update brings many new features to iOS devices, including support for ARKit-based augmented reality apps, advanced multitasking and more.