When a node (or user profile) is modified, is it possible to send an email notification only when a specified field is modified?
With the node I have no problem, but I cannot get it to work for a specific field.
You can use the Rules module for this. Here are some details about how to do so:
Should be straight forward to "develop" such rule, no (PHP) coding at all involved (only site building using admin UI).
Have a look at hook_user_update. This hook is called when a user account (user profile?) is updated.
You might also want to look at hook_node_update. You will not be able to use the hook_node_update
to be notified when your user accounts are updated, but on this page there is a comment about $node->original
having the values of the $node
before the update.
I have not tested this myself (should be a trivial excursive), but you may be lucky and find $account->original (or something similar) stores the original values of the user account.
It is then a simple matter of testing the old field value against the new one to see if a change occurred, and you can take appropriate action - like sending a mail.