The Exchange 2000 remote server or the Exchange 2003 remote server is out of disk storage to hold mail. This issue occurs ...

{4}: The Exchange 2000 remote server or the Exchange 2003 remote server is out of disk storage to hold mail. This issue occurs most frequently when the sending server is sending mail with binary DATA (BDAT). This code may also indicate an SMTP protocol error. Troubleshooting: Make sure the remote server has sufficient storage to hold mail, and examine the SMTP protocol log for errors.