We are using Outlook 2007 and Exchange 2000 Server Standard. I have not put a recipient limit on the Exchange server or on the individual mailboxes. Is there a limit to the number of recipients that Exchange can handle? Here is why I ask - this morning, one of our staff members sent a single email message to about 1000 recipients. She did not receive an error and my Exchange server did not throw any errors (even in the Event Log). However, it was at the same time that the email was sent that my Exchange Server stopped sending/receiving external emails. Rebooting the Exchange Server corrected the problem. I am trying to figure out if they are related. What would be a reasonable limit to set on each user's mailbox?