For the last few years the largest email message you could send or receive in Office 365 was 25 MB. While 25 MB is more than enough for the majority of email, you might bump up against that limit when trying to send large slide decks, spreadsheets or videos. We’re pleased to announce that Microsoft has increased the allowed maximum message size to 150 MB effective immediately.
Note: You may be able to send and receive large messages up to 150 MB, but your associates outside your organization may not. Whether it’s because their mail is hosted on a different email service or system that doesn’t support large message sizes, or they’re an Office 365 customer but haven’t changed their settings, they may not be able to receive your large message.