Email Message Limits Size and Recipients

The hosted Exchange server has limits set for each email message that can be sent or received:

• Maximum Message Size - The maximum message size is 20 MB which includes the body of the messages and any attachments. When calculating message size it is important to remember that any binary attachments, such as images or software, increase in size by approximately 30 percent when sent via email.
  
• Maximum Number of Recipients - An email message cannot be sent to more than 500 email addresses via the To, CC, and BCC fields. If you need to send a message to more than 500 recipients, you will need to send it in blocks of 500 recipients.