macro can be used to get status of problem.
According to the documentation:

Numeric value of the event that triggered an action (1 for problem, 0 for recovering).

Consider the following use case:

1. Create trapper item (item trap on host hvost)
2. Create trigger {hvost:trap.last()}=1
3. Create two media types (email and webhook) and add messages for problem, resolve and update (use {EVENT.VALUE} macro in both email messages and webhook).
4. Send value 1 for trapper item. Problem is generated, and messages are sent.
5. Send value 0 for trapper item. Problem is resolved, messages are sent.
6. Use problem acknowledge dialog to leave a message (different user should be used to get notifications) without changing anything else.
7. Observe that {EVENT.VALUE} macro is valid for email, but is not valid for webhook (showing 1 instead of 0).

Results for email (macro used in subject, value is number in brackets):

Results for webhook (webhool throws values or three macros, last one is
{EVENT.VALUE}):