diff --git a/index.html b/index.html
index bf56b81..faa52b0 100644
--- a/index.html
+++ b/index.html
@@ -798,68 +798,63 @@
                         <div id="mailbox-form-container" style="display:none;margin-top:1rem;padding:1rem;background:#f8f9fb;border-radius:8px;">
                             <h4 style="color:#0f3460;margin-bottom:0.75rem;" id="mailbox-form-title">Uusi postilaatikko</h4>
                             <input type="hidden" id="mailbox-form-id">
-                            <div class="form-grid" style="max-width:600px;">
-                                <div class="form-group full-width">
-                                    <label>Nimi (näkyy tikettilistassa) *</label>
-                                    <input type="text" id="mailbox-form-nimi" placeholder="esim. Asiakaspalvelu">
+                            <div style="max-width:700px;">
+                                <div class="form-grid">
+                                    <div class="form-group full-width">
+                                        <label>Nimi (näkyy tikettilistassa) *</label>
+                                        <input type="text" id="mailbox-form-nimi" placeholder="esim. Asiakaspalvelu">
+                                    </div>
                                 </div>
-                                <div class="form-group">
-                                    <label>IMAP-palvelin</label>
-                                    <input type="text" id="mailbox-form-host" placeholder="mail.example.com">
+                                <!-- Saapuva + Lähtevä vierekkäin -->
+                                <div style="display:grid;grid-template-columns:1fr 1fr;gap:1.5rem;margin-top:0.5rem;">
+                                    <!-- Saapuva posti (IMAP) -->
+                                    <div>
+                                        <h4 style="color:#0f3460;font-size:0.9rem;margin:0 0 0.5rem;">Saapuva posti (IMAP)</h4>
+                                        <div class="form-group"><label>Palvelin</label><input type="text" id="mailbox-form-host" placeholder="mail.example.com"></div>
+                                        <div class="form-group"><label>Portti</label><input type="number" id="mailbox-form-port" value="993" placeholder="993"></div>
+                                        <div class="form-group"><label>Käyttäjätunnus</label><input type="text" id="mailbox-form-user" placeholder="asiakaspalvelu@yritys.fi"></div>
+                                        <div class="form-group"><label>Salasana</label><input type="password" id="mailbox-form-password" placeholder="••••••••"></div>
+                                        <div class="form-group"><label>Salaus</label>
+                                            <select id="mailbox-form-encryption">
+                                                <option value="ssl">SSL</option>
+                                                <option value="tls">TLS</option>
+                                                <option value="notls">Ei salausta</option>
+                                            </select>
+                                        </div>
+                                    </div>
+                                    <!-- Lähtevä posti (SMTP) -->
+                                    <div>
+                                        <h4 style="color:#0f3460;font-size:0.9rem;margin:0 0 0.5rem;">Lähtevä posti (SMTP)</h4>
+                                        <div class="form-group">
+                                            <label style="display:flex;align-items:center;gap:0.4rem;cursor:pointer;">
+                                                <input type="checkbox" id="mailbox-form-smtp-same" checked> Käytä samoja tunnuksia kuin saapuvassa
+                                            </label>
+                                        </div>
+                                        <div id="smtp-custom-fields">
+                                            <div class="form-group"><label>Palvelin</label><input type="text" id="mailbox-form-smtp-host" placeholder="mail.yritys.fi"></div>
+                                            <div class="form-group"><label>Portti</label><input type="number" id="mailbox-form-smtp-port" value="587" placeholder="587"></div>
+                                            <div class="form-group"><label>Käyttäjätunnus</label><input type="text" id="mailbox-form-smtp-user" placeholder="asiakaspalvelu@yritys.fi"></div>
+                                            <div class="form-group"><label>Salasana</label><input type="password" id="mailbox-form-smtp-pass" placeholder="••••••••"></div>
+                                            <div class="form-group"><label>Salaus</label>
+                                                <select id="mailbox-form-smtp-encryption">
+                                                    <option value="tls">STARTTLS</option>
+                                                    <option value="ssl">SSL</option>
+                                                    <option value="none">Ei salausta</option>
+                                                </select>
+                                            </div>
+                                        </div>
+                                    </div>
                                 </div>
-                                <div class="form-group">
-                                    <label>Portti</label>
-                                    <input type="number" id="mailbox-form-port" value="993" placeholder="993">
-                                </div>
-                                <div class="form-group">
-                                    <label>Käyttäjätunnus</label>
-                                    <input type="text" id="mailbox-form-user" placeholder="asiakaspalvelu@yritys.fi">
-                                </div>
-                                <div class="form-group">
-                                    <label>Salasana</label>
-                                    <input type="password" id="mailbox-form-password" placeholder="••••••••">
-                                </div>
-                                <div class="form-group">
-                                    <label>Salaus</label>
-                                    <select id="mailbox-form-encryption">
-                                        <option value="ssl">SSL</option>
-                                        <option value="tls">TLS</option>
-                                        <option value="notls">Ei salausta</option>
-                                    </select>
-                                </div>
-                                <div class="form-group">
-                                    <label>Lähettäjän sähköposti</label>
-                                    <input type="text" id="mailbox-form-smtp-email" placeholder="asiakaspalvelu@yritys.fi">
-                                </div>
-                                <div class="form-group">
-                                    <label>Lähettäjän nimi</label>
-                                    <input type="text" id="mailbox-form-smtp-name" placeholder="Yritys Asiakaspalvelu">
-                                </div>
-                                <h4 style="margin:1rem 0 0.5rem;color:#0f3460;font-size:0.9rem;">SMTP-lähetysasetukset</h4>
-                                <p style="font-size:0.78rem;color:#888;margin-bottom:0.5rem;">Jätä tyhjäksi käyttääksesi palvelimen omaa sendmailia</p>
-                                <div class="form-group">
-                                    <label>SMTP-palvelin</label>
-                                    <input type="text" id="mailbox-form-smtp-host" placeholder="mail.yritys.fi">
-                                </div>
-                                <div class="form-group">
-                                    <label>SMTP-portti</label>
-                                    <input type="number" id="mailbox-form-smtp-port" value="587" placeholder="587">
-                                </div>
-                                <div class="form-group">
-                                    <label>SMTP-käyttäjä</label>
-                                    <input type="text" id="mailbox-form-smtp-user" placeholder="asiakaspalvelu@yritys.fi">
-                                </div>
-                                <div class="form-group">
-                                    <label>SMTP-salasana</label>
-                                    <input type="password" id="mailbox-form-smtp-pass" placeholder="••••••••">
-                                </div>
-                                <div class="form-group">
-                                    <label>SMTP-salaus</label>
-                                    <select id="mailbox-form-smtp-encryption">
-                                        <option value="tls">STARTTLS</option>
-                                        <option value="ssl">SSL</option>
-                                        <option value="none">Ei salausta</option>
-                                    </select>
+                                <!-- Lähettäjätiedot -->
+                                <div class="form-grid" style="margin-top:0.75rem;">
+                                    <div class="form-group">
+                                        <label>Lähettäjän sähköposti</label>
+                                        <input type="text" id="mailbox-form-smtp-email" placeholder="asiakaspalvelu@yritys.fi">
+                                    </div>
+                                    <div class="form-group">
+                                        <label>Lähettäjän nimi</label>
+                                        <input type="text" id="mailbox-form-smtp-name" placeholder="Yritys Asiakaspalvelu">
+                                    </div>
                                 </div>
                             </div>
                             <div style="display:flex;gap:0.5rem;margin-top:0.75rem;">
diff --git a/script.js b/script.js
index 9c1a530..251c929 100644
--- a/script.js
+++ b/script.js
@@ -2532,9 +2532,24 @@ function showMailboxForm(mb = null) {
     document.getElementById('mailbox-form-smtp-user').value = mb ? (mb.smtp_user || '') : '';
     document.getElementById('mailbox-form-smtp-pass').value = mb ? (mb.smtp_password || '') : '';
     document.getElementById('mailbox-form-smtp-encryption').value = mb ? (mb.smtp_encryption || 'tls') : 'tls';
+    // "Käytä samoja tunnuksia" — oletuksena päällä uudelle, olemassa olevalle tarkistetaan
+    const sameCheck = document.getElementById('mailbox-form-smtp-same');
+    if (mb) {
+        // Jos SMTP-host on tyhjä tai sama kuin IMAP -> samoja tunnuksia
+        const smtpIsSame = !mb.smtp_host || mb.smtp_host === mb.imap_host;
+        sameCheck.checked = smtpIsSame;
+    } else {
+        sameCheck.checked = true;
+    }
+    toggleSmtpFields();
     document.getElementById('mailbox-form-container').style.display = '';
 }
 
+function toggleSmtpFields() {
+    const same = document.getElementById('mailbox-form-smtp-same').checked;
+    document.getElementById('smtp-custom-fields').style.display = same ? 'none' : '';
+}
+
 function editMailbox(id) {
     const mb = mailboxesData.find(m => m.id === id);
     if (mb) showMailboxForm(mb);
@@ -2548,22 +2563,30 @@ async function deleteMailbox(id, nimi) {
     } catch (e) { alert(e.message); }
 }
 
+// SMTP "Käytä samoja tunnuksia" -checkbox toggle
+document.getElementById('mailbox-form-smtp-same').addEventListener('change', toggleSmtpFields);
+
 document.getElementById('btn-save-mailbox').addEventListener('click', async () => {
+    const useSame = document.getElementById('mailbox-form-smtp-same').checked;
+    const imapHost = document.getElementById('mailbox-form-host').value;
+    const imapUser = document.getElementById('mailbox-form-user').value;
+    const imapPass = document.getElementById('mailbox-form-password').value;
+    const imapEnc = document.getElementById('mailbox-form-encryption').value;
     const data = {
         id: document.getElementById('mailbox-form-id').value || undefined,
         nimi: document.getElementById('mailbox-form-nimi').value,
-        imap_host: document.getElementById('mailbox-form-host').value,
+        imap_host: imapHost,
         imap_port: parseInt(document.getElementById('mailbox-form-port').value) || 993,
-        imap_user: document.getElementById('mailbox-form-user').value,
-        imap_password: document.getElementById('mailbox-form-password').value,
-        imap_encryption: document.getElementById('mailbox-form-encryption').value,
+        imap_user: imapUser,
+        imap_password: imapPass,
+        imap_encryption: imapEnc,
         smtp_from_email: document.getElementById('mailbox-form-smtp-email').value,
         smtp_from_name: document.getElementById('mailbox-form-smtp-name').value,
-        smtp_host: document.getElementById('mailbox-form-smtp-host').value,
-        smtp_port: parseInt(document.getElementById('mailbox-form-smtp-port').value) || 587,
-        smtp_user: document.getElementById('mailbox-form-smtp-user').value,
-        smtp_password: document.getElementById('mailbox-form-smtp-pass').value,
-        smtp_encryption: document.getElementById('mailbox-form-smtp-encryption').value,
+        smtp_host: useSame ? imapHost : document.getElementById('mailbox-form-smtp-host').value,
+        smtp_port: useSame ? 587 : (parseInt(document.getElementById('mailbox-form-smtp-port').value) || 587),
+        smtp_user: useSame ? imapUser : document.getElementById('mailbox-form-smtp-user').value,
+        smtp_password: useSame ? imapPass : document.getElementById('mailbox-form-smtp-pass').value,
+        smtp_encryption: useSame ? 'tls' : document.getElementById('mailbox-form-smtp-encryption').value,
         aktiivinen: true,
     };
     try {