In TIBCO Scribe® Insight, if you receive the error shown below, it indicates an issue with the SMTP server that Insight is using the send the alerts. 

"Unexpected Send Mail error: Insufficient system storage. The server response was: 4.5.3 Too many recipients (AS780090)"

This is a warning from the SMTP server, and indicates that the number of Alert recipients configured in the Scribe Insight Console has exceeded a limit configured for the SMTP server.

There are two ways you could resolve this error.

1) Remove some Recipients who are no longer required.

•     Expand the Console site node.
•     Expand the Administration node, and then click Alert Recipients. The Alert Recipients window opens.
•     Go to the Recipients area of the window, and select the Recipient you wish to delete.
•     Click Delete.