Our Exchange system has limits set for each e-mail message that can be sent or received through our mail servers:
Maximum Message Size = 100 MB. This includes the body of the messages and any attachments.
Note: Any binary attachments (images, software, etc.) increase in size by about 30 percent when sent via e-mail, so that needs to be factored in when calculating maximum message size.
Maximum Number of Recipients = 500. An e-mail message cannot be sent to more than 500 e-mail addresses (via
the To, CC, and BCC fields). If you need to send a message to more than 500 recipients, you will have to send it to 500 recipients at a time.