All Exchange accounts can receive messages of up to 100 MB in size, but will vary in terms of messages that can be sent. It’s important to note that message size includes the message itself, plus attachments, plus any encoding that is placed on the message by the sending mail client (which could, for example, make a 99 MB file too large). See details below:

Mail Client

Send Limit

Receive Limit

Outlook Web Access (OWA – xmail.bu.edu) 50 MB 100 MB
Outlook 2007 and 2010 (Windows) 100 MB 100 MB
Outlook 2011 (Mac) 50 MB 100 MB
Mail (Mac) 50 MB 100 MB
IMAP clients 100 MB 100 MB