Re: Critical parts goes below Re-order pt - to trigger email via Workflow

first of all check for a standard event when executing the movement type (check the event trace SWEL),

in none exist, there are many ways to raise an event for example using change documents (SWEC) or a user exit calling FM SAP_WAPI_CREAT_EVENT.

You can create a starting condition in SWB_COND or use a check function module in the event linkage in SWE2 in order to limit the sending of the mail to only when the stock is below the re-order point.