Before Christmas I was looking at ways to send different email alerts from a single rule in SCOM (rather than creating different alert rules for each type of informational message I wanted sent out). I explored Custom Alert Fields - using Custom Alert Field 1 to hold some general text about the error and some support instructions.
I then configured two subscriptions to the same alerts - one using the alert information and full detail I specified in the alert description (for 3rd line support/developers) and the other using Custom Alert Field 1 for the general support team.
However, I seem to have found a limitation. While the GUI allows you to input more than 256 characters into a Custom Alert Field, when you use the field in an email, the text is truncated to the first 256 characters. Until I can find any other answers to this, I've amended my text to less than this limit.
I could of course use other custom fields if I really needed to go beyond the display limit although I assume each one will cut off at 256 when used.