Auto-Action: How to send Email only 1 time onAfterUserUpdate ?

hello

I would like send only one time a warning message to user when he tick/un-tick a specific checkbox of his profile.


The problem is I would like fire this action with onAfterUserUpdate but if I use this trigger, the message will be sent on each profile update and not only if the related field is changed.

I don't see which condition or trigger I could use for send only one time the message.

Any clue ?

Check that your checkbox field has changed using the below conditional usage.

[var1_FIELD_NAME] Not Equal To [var3_FIELD_NAME]

var1 is the new user object with updated field values. var3 is the old user object with the old field values (unchanged). This allows you to compare the new and the old values to see if they match or not. In the above usage it checks to see if the values no longer match one another.