Merge pull request #3837 from egeoztass/fix/email-error-propagation

fix: propagate SMTP transport errors from EmailService.sendEmail

server/src/api/controllers/settingsController.ts

@@ -93,24 +93,30 @@ class SettingsController implements ISettingsController {
 		if (!html) {
 			throw new AppError({ message: "Failed to build email template.", status: 500 });
 		}
-		const messageId = await this.emailService.sendEmail(to, subject, html, {
-			systemEmailHost,
-			systemEmailPort,
-			systemEmailUser,
-			systemEmailAddress,
-			systemEmailDisplayName,
-			systemEmailPassword,
-			systemEmailConnectionHost,
-			systemEmailSecure,
-			systemEmailPool,
-			systemEmailIgnoreTLS,
-			systemEmailRequireTLS,
-			systemEmailRejectUnauthorized,
-			systemEmailTLSServername,
-		});
-
-		if (!messageId) {
-			throw new AppError({ message: "Failed to send test email.", status: 500 });
+		let messageId: string;
+		try {
+			messageId = await this.emailService.sendEmail(to, subject, html, {
+				systemEmailHost,
+				systemEmailPort,
+				systemEmailUser,
+				systemEmailAddress,
+				systemEmailDisplayName,
+				systemEmailPassword,
+				systemEmailConnectionHost,
+				systemEmailSecure,
+				systemEmailPool,
+				systemEmailIgnoreTLS,
+				systemEmailRequireTLS,
+				systemEmailRejectUnauthorized,
+				systemEmailTLSServername,
+			});
+		} catch (error: unknown) {
+			// Surface the underlying SMTP failure: diagnosing the settings is the whole
+			// point of the test email endpoint.
+			throw new AppError({
+				message: error instanceof Error ? `Failed to send test email. ${error.message}` : "Failed to send test email.",
+				status: 500,
+			});
 		}
 
 		return res.status(200).json({