diff --git a/main.go b/main.go
index 36a7cd0..e0208e4 100644
--- a/main.go
+++ b/main.go
@@ -159,8 +159,8 @@ func postMessage(conf Config, msg Message) error {
 		return fmt.Errorf("server error: %s, response: %s", resp.Status, body)
 	}
 
-	if err := exportOutputs(&conf, resp); err != nil {
-		return fmt.Errorf("failed to export outputs: %s", err)
+	if err := processResponse(&conf, resp); err != nil {
+		return err
 	}
 
 	return nil
@@ -176,6 +176,11 @@ func validate(conf *Config) error {
 		conf.WebhookURL = ""
 
 	}
+
+	if conf.APIToken == "" && isRequestingOutput(conf) {
+		return fmt.Errorf("Outputs can only be set when using the API Token.")
+	}
+
 	return nil
 }
 
diff --git a/outputs.go b/outputs.go
index a47a7f2..e804eca 100644
--- a/outputs.go
+++ b/outputs.go
@@ -5,32 +5,31 @@ import (
 	"fmt"
 	"net/http"
 	"os/exec"
-	"strings"
 
 	"github.com/bitrise-io/go-utils/log"
 )
 
 // SendMessageResponse is the response from Slack POST
+// https://api.slack.com/methods/chat.postMessage#examples
 type SendMessageResponse struct {
+	/// The status of the request. When `false`, check the Error for a reason
+	Ok bool `json:"ok"`
+
+	/// Describes an error that prevented the message from being sent
+	Error string `json:"error"`
+
 	/// The Thread Timestamp
 	Timestamp string `json:"ts"`
 }
 
-/// Export the output variables after a successful response
-func exportOutputs(conf *Config, resp *http.Response) error {
-
-	if !isRequestingOutput(conf) {
-		log.Debugf("Not requesting any outputs")
+// Check the response status and set any output variables if required
+func processResponse(conf *Config, resp *http.Response) error {
+	// if the request was made using a legacy webhook url, skip processing as there is no response.
+	if conf.APIToken == "" {
+		log.Debugf("Skipping response processing because legacy webhook urls do not return any content")
 		return nil
 	}
 
-	isWebhook := strings.TrimSpace(selectValue(string(conf.WebhookURL), string(conf.WebhookURLOnError))) != ""
-
-	// Slack webhooks do not return any useful response information
-	if isWebhook {
-		return fmt.Errorf("For output support, do not submit a WebHook URL")
-	}
-
 	var response SendMessageResponse
 	parseError := json.NewDecoder(resp.Body).Decode(&response)
 	if parseError != nil {
@@ -38,6 +37,11 @@ func exportOutputs(conf *Config, resp *http.Response) error {
 		return fmt.Errorf("Failed to parse response: %s", parseError)
 	}
 
+	// if slack didn't return 'ok', fail with the error code
+	if !response.Ok {
+		return fmt.Errorf("Slack responded with error: %s", response.Error)
+	}
+
 	if string(conf.ThreadTsOutputVariableName) != "" {
 		log.Debugf("Exporting output: %s=%s\n", string(conf.ThreadTsOutputVariableName), response.Timestamp)
 		err := exportEnvVariable(string(conf.ThreadTsOutputVariableName), response.Timestamp)
@@ -50,12 +54,12 @@ func exportOutputs(conf *Config, resp *http.Response) error {
 
 }
 
-/// Checks if we are requesting an output of anything
+// Checks if we are requesting an output of anything
 func isRequestingOutput(conf *Config) bool {
 	return string(conf.ThreadTsOutputVariableName) != ""
 }
 
-/// Exports env using envman
+// Exports env using envman
 func exportEnvVariable(variable string, value string) error {
 	c := exec.Command("envman", "add", "--key", variable, "--value", value)
 	err := c.Run()