New Outlook for Windows will soon let you add attachments offline

Earlier this week, Microsoft announced that it’ll be blocking more file types in New Outlook and the web version of the email client. Well, here’s yet another update—but this one’s all about improving how attachments work offline in the New Outlook for Windows.

Starting July 2025, you’ll be able to add attachments to emails even when you’re completely offline. The feature quietly showed up on the Microsoft 365 roadmap under message ID 496371.

Last December, Microsoft added support for opening attachments offline. That’s already a big help for anyone working on the go or dealing with spotty connections. Now, with the ability to add attachments in offline mode, the experience finally feels more complete.

Microsoft’s been steadily adding offline support in New Outlook. Just last month, it added calendar access without needing a connection. These upgrades seem designed to reduce reliance on the Classic Outlook app and get more users comfortable making the switch.

In contrast, Classic Outlook hasn’t had the smoothest ride lately. Microsoft’s recent calendar feature update triggered several bugs, and the company had to publish workarounds to keep things functional.