set reply-to header in automated emails

Signed-off-by: eternal-flame-AD <yume@yumechi.jp>

packages/backend/src/core/EmailService.ts

@@ -145,6 +145,7 @@ export class EmailService {
 		try {
 			// TODO: htmlサニタイズ
 			const info = await transporter.sendMail({
+				inReplyTo: this.meta.maintainerEmail ? { name: this.meta.maintainerName || 'Instance Maintainer', address: this.meta.maintainerEmail } : undefined,
 				from: this.meta.email!,
 				to: to,
 				subject: subject,