Microsoft announced they're going to increase the email message size limit to 150 MB for Office 365 users, allowing them to send large files as attachments when needed. Previously, the largest message you could send or receive in Office 365 was 25 MB, so it's decent jump, and will be helpful for users who often find themselves sending large files as attachments in an email.
Office 365 users also have the ability to save the file in a OneDrive for Business account and share it with their colleagues, but some people often find it easier to just open the compose message window and attach it right away, rather than first going to OneDrive, uploading it, and then attaching it to the email.
However, the default file size is still set to 25 MB -- it depends on the Office 365 admins to set the maximum file size limit which ranges from 1 MB to 150 MB.
"We’re pleased to announce that we’ve increased the allowed maximum message size to 150 MB, giving Office 365 administrators the ability to set the maximum message size of their choosing from 1 MB up to 150 MB," Microsoft said in a blog post.