The size of the email message you could send or receive in Office 365 was 25 MB since its launch. Whenever, you try to send large slide decks, spreadsheets or videos, you will get an error email. All these years, Microsoft was citing the Outlook Web App (OWA) feature that lets you to “attach” a document as a link to where it’s saved on OneDrive for Business. But many users wanted to send it as a direct attachment and so Microsoft is announcing that they’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.
The default maximum message size for Office 365 mailboxes is still 25 MB, and we aren’t going to change the setting on existing accounts. It turns out that some folks want an even smaller setting than 25 MB and many don’t want to change the current setting at all. So instead of us foisting a one-size-fits-all setting onto everyone, we’re now giving Office 365 customers the freedom to choose the maximum size setting that’s right for them.
Read more about it here.