fix(mail): align queue, outbound hostname, and DKIM selector behavior across the mail server APIs

ts/mail/routing/classes.dns.manager.ts

@@ -1,5 +1,6 @@
 import * as plugins from '../../plugins.js';
 import type { IEmailDomainConfig } from './interfaces.js';
+import type { IStorageManagerLike } from '../interfaces.storage.js';
 import { logger } from '../../logger.js';
 /** External DcRouter interface shape used by DnsManager */
 interface IDcRouterLike {
@@ -8,12 +9,6 @@ interface IDcRouterLike {
   options?: { dnsNsDomains?: string[]; dnsScopes?: string[] };
 }
 
-/** External StorageManager interface shape used by DnsManager */
-interface IStorageManagerLike {
-  get(key: string): Promise<string | null>;
-  set(key: string, value: string): Promise<void>;
-}
-
 /**
  * DNS validation result
  */
@@ -528,7 +523,7 @@ export class DnsManager {
       
       try {
         // Get DKIM DNS record from DKIMCreator
-        const dnsRecord = await dkimCreator.getDNSRecordForDomain(domain);
+        const dnsRecord = await dkimCreator.getDNSRecordForDomain(domain, selector);
         
         // For internal-dns domains, register the DNS handler
         if (domainConfig.dnsMode === 'internal-dns' && this.dcRouter.dnsServer) {
@@ -570,4 +565,4 @@ export class DnsManager {
       }
     }
   }
-}
+}