diff --git a/apps/super-admin/src/components/EmailDnsModal.tsx b/apps/super-admin/src/components/EmailDnsModal.tsx
index e884d12..1319398 100644
--- a/apps/super-admin/src/components/EmailDnsModal.tsx
+++ b/apps/super-admin/src/components/EmailDnsModal.tsx
@@ -14,28 +14,27 @@ interface EmailDnsModalProps {
   onClose: () => void
 }
 
+const DEFAULT_ED25519_SELECTOR = 'v1-ed25519-20260901'
+const DEFAULT_RSA_SELECTOR = 'v1-rsa-20260901'
+
 function pasteIncludesDomainkey(paste: string) {
   return /[a-z0-9][a-z0-9-]*\._domainkey/i.test(paste)
 }
 
-function keyReady(paste: string, selector: string) {
-  const trimmed = paste.trim()
-  if (!trimmed) return false
-  return pasteIncludesDomainkey(trimmed) || Boolean(selector.trim())
-}
-
-/** Empty = skip Ed25519; otherwise same rules as RSA. */
-function optionalKeyReady(paste: string, selector: string) {
-  if (!paste.trim()) return true
-  return keyReady(paste, selector)
+/** Prefer typed selector; otherwise default when the paste has no …._domainkey. */
+function resolveSelector(paste: string, selector: string, fallback: string) {
+  const typed = selector.trim()
+  if (typed) return typed
+  if (pasteIncludesDomainkey(paste)) return ''
+  return fallback
 }
 
 export function EmailDnsModal({ domain, onClose }: EmailDnsModalProps) {
   const { showToast } = useToast()
   const [dnsProvider, setDnsProvider] = useState<ParkedDnsProvider>('arvan')
-  const [ed25519Selector, setEd25519Selector] = useState('')
+  const [ed25519Selector, setEd25519Selector] = useState(DEFAULT_ED25519_SELECTOR)
   const [ed25519Key, setEd25519Key] = useState('')
-  const [rsaSelector, setRsaSelector] = useState('')
+  const [rsaSelector, setRsaSelector] = useState(DEFAULT_RSA_SELECTOR)
   const [rsaKey, setRsaKey] = useState('')
   const [submitting, setSubmitting] = useState(false)
   const [error, setError] = useState('')
@@ -43,9 +42,9 @@ export function EmailDnsModal({ domain, onClose }: EmailDnsModalProps) {
   useEffect(() => {
     if (!domain) return
     setDnsProvider('arvan')
-    setEd25519Selector('')
+    setEd25519Selector(DEFAULT_ED25519_SELECTOR)
     setEd25519Key('')
-    setRsaSelector('')
+    setRsaSelector(DEFAULT_RSA_SELECTOR)
     setRsaKey('')
     setError('')
     setSubmitting(false)
@@ -53,23 +52,50 @@ export function EmailDnsModal({ domain, onClose }: EmailDnsModalProps) {
 
   if (!domain) return null
   const target = domain
-  const canSubmit =
-    keyReady(rsaKey, rsaSelector) &&
-    optionalKeyReady(ed25519Key, ed25519Selector)
+  const canSubmit = Boolean(rsaKey.trim())
 
   async function submit() {
+    if (!rsaKey.trim()) {
+      const message = 'Paste the RSA DKIM TXT value from Stalwart.'
+      setError(message)
+      showToast(message, 'error')
+      return
+    }
+
+    const ed25519Paste = ed25519Key.trim()
+    const rsaPaste = rsaKey.trim()
+    const resolvedRsaSelector = resolveSelector(
+      rsaPaste,
+      rsaSelector,
+      DEFAULT_RSA_SELECTOR,
+    )
+    const resolvedEd25519Selector = ed25519Paste
+      ? resolveSelector(
+          ed25519Paste,
+          ed25519Selector,
+          DEFAULT_ED25519_SELECTOR,
+        )
+      : ''
+
+    // Show resolved defaults in the fields if they were cleared.
+    if (!rsaSelector.trim() && resolvedRsaSelector) {
+      setRsaSelector(resolvedRsaSelector)
+    }
+    if (ed25519Paste && !ed25519Selector.trim() && resolvedEd25519Selector) {
+      setEd25519Selector(resolvedEd25519Selector)
+    }
+
     setSubmitting(true)
     setError('')
     try {
-      const ed25519Paste = ed25519Key.trim()
       const result = await applyMailDns(target.id, {
         dnsProvider,
-        rsaKey,
+        rsaKey: rsaPaste,
+        ...(resolvedRsaSelector ? { rsaSelector: resolvedRsaSelector } : {}),
         ...(ed25519Paste ? { ed25519Key: ed25519Paste } : {}),
-        ...(ed25519Paste && ed25519Selector.trim()
-          ? { ed25519Selector: ed25519Selector.trim() }
+        ...(ed25519Paste && resolvedEd25519Selector
+          ? { ed25519Selector: resolvedEd25519Selector }
           : {}),
-        ...(rsaSelector.trim() ? { rsaSelector: rsaSelector.trim() } : {}),
       })
       showToast(result.message, 'success')
       onClose()
@@ -95,14 +121,14 @@ export function EmailDnsModal({ domain, onClose }: EmailDnsModalProps) {
       <p className={parkedStyles.hint}>
         Paste the RSA DKIM <strong>TXT value</strong> (<code>v=DKIM1; …</code>) from
         Stalwart, or the full zone line. Ed25519 is optional — leave it empty to
-        skip. For value-only pastes, fill the selector (for example{' '}
-        <code>v1-rsa-20260901</code>). We upsert common mail records on{' '}
-        {dnsProvider === 'cloudflare' ? 'Cloudflare' : 'Arvan'} (DNS-only / not
-        proxied): <strong>mail</strong> A → 185.214.101.41, MX → mail.meshkee.com
-        (priority 10), SPF <code>v=spf1 mx -all</code>, DKIM (RSA required,
-        Ed25519 if provided), autoconfig / autodiscover → mail.meshkee.com. Extra
-        MX, <strong>dkim._domainkey</strong>, and <strong>_dmarc</strong> are
-        removed.
+        skip. Selectors default to <code>{DEFAULT_RSA_SELECTOR}</code> /{' '}
+        <code>{DEFAULT_ED25519_SELECTOR}</code> when empty. We upsert common mail
+        records on {dnsProvider === 'cloudflare' ? 'Cloudflare' : 'Arvan'}{' '}
+        (DNS-only / not proxied): <strong>mail</strong> A → 185.214.101.41, MX →
+        mail.meshkee.com (priority 10), SPF <code>v=spf1 mx -all</code>, DKIM
+        (RSA required, Ed25519 if provided), autoconfig / autodiscover →
+        mail.meshkee.com. Extra MX, <strong>dkim._domainkey</strong>, and{' '}
+        <strong>_dmarc</strong> are removed.
       </p>
       {error ? (
         <p className={tableStyles.alertError} role="alert">
@@ -134,14 +160,14 @@ export function EmailDnsModal({ domain, onClose }: EmailDnsModalProps) {
           type="text"
           value={ed25519Selector}
           onChange={(e) => setEd25519Selector(e.target.value)}
-          placeholder="v1-ed25519-20260901"
+          placeholder={DEFAULT_ED25519_SELECTOR}
           disabled={submitting}
           spellCheck={false}
           dir="ltr"
           autoComplete="off"
         />
         <p className={tableStyles.helperText}>
-          Only needed with an Ed25519 paste that has no <code>…._domainkey</code>.
+          Auto-filled when empty. Change it if Stalwart uses a different selector.
         </p>
       </div>
       <div className={tableStyles.field}>
@@ -170,15 +196,14 @@ export function EmailDnsModal({ domain, onClose }: EmailDnsModalProps) {
           type="text"
           value={rsaSelector}
           onChange={(e) => setRsaSelector(e.target.value)}
-          placeholder="v1-rsa-20260901"
+          placeholder={DEFAULT_RSA_SELECTOR}
           disabled={submitting}
           spellCheck={false}
           dir="ltr"
           autoComplete="off"
         />
         <p className={tableStyles.helperText}>
-          Needed when pasting only the TXT value. Optional if the paste includes{' '}
-          <code>…._domainkey</code>.
+          Auto-filled when empty. Change it if Stalwart uses a different selector.
         </p>
       </div>
       <div className={tableStyles.field}>