

Simply select recipients > mailboxes then click “.” and select Set default message size restrictions. You can change the default for your organization by adjusting the default message size restriction. You customize the message size in the Exchange Admin Center, which requires global administrator role privileges. Whatever custom configuration you want to apply, whether for one, some, or all your mailboxes you can do it-as long as it’s between 1 MB and 150 MB.

Do you have a hybrid mail configuration (some mailboxes on-premises, some in the cloud) and you want a consistent 10 MB restriction regardless where the mailbox is hosted? We have you covered. Want to restrict students in your school from sending messages larger than 5 MB, while the faculty can send up to 50 MB? No problem. Want to go wild and allow everyone to send and receive 100 MB size messages? Go for it. You can customize the maximum allowed message size for any and all your mailboxes however you see fit. 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. 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. 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.
