Auto action, send a mail when field is given a val

Is it possible to add an auto action that reacts when a user field is changed to a specific value?

I would like to send a mail when a field is changed from 'not payed' to another value.
I can see that I have a trigger that I can set when profile is modified in the frontend or backend, but how do I make a condition so it will only send a mail if the value in question is changed?

My idea so far is:

Type: Email
Triggers: onAfterUserUpdate,onAfterUpdateUser
User: Automatic
Access: Everybody
Conditional: ??? NOT EQUAL TO 'not payed'
Email action:

Conditions support full substitutions (see info directly next to input for details and special functions). You could for example use the below.

Left: [cb_myfield]
Operator: Not Equal To
Right: not payed

But this action will send a mail EVERY time the profile is changed?

Yes, if that condition is met it will.

If you want it to send only 1 time when the field is changed you could use the below (requires 2 conditions)

Condition 1
Left: [cb_myfield]
Operator: Not Equal To
Right: [var4_cb_myfield]

Condition 2
Left: [cb_myfield]
Operator: Not Equal To
Right: not payed

Note in the above the "var4". The 4th variable provided by these triggers is the previous values. This means [cb_myfield] will be what I just change the field to and [var4_cb_myfield] will be what I just changed the field from.

Hey, neat! Thankyou!

Ok, maybe you can explain to me what I'm doing wrong.

I've created a test user, and I've set him to 'Endnu ikke betalt'.
Then I go in, via the backend, and change the value to '2012'
The field cb_betalt is a multiselect field.
As I understand it, the rule below both triggers on frontend and backend profile modification, and with the very neat var4, asks for the value before and after.

The conditions are not what I supplied, please see my previous reply. The first condition needs to first check if the field was even changed. That's done with the below.

[cb_betalt] Not Equal To [var4_cb_betalt]

If the above passes it means the fields value differs from the previous meaning it was changed. After that you can do your matching for a value such as the below.

[cb_betalt] Does Contain 2012

Ah, yes, I misunderstood, I'll give it a go, excellent, thanks!