diff --git a/data/web/api/openapi.yaml b/data/web/api/openapi.yaml
index 969aa7707..7fb4af308 100644
--- a/data/web/api/openapi.yaml
+++ b/data/web/api/openapi.yaml
@@ -409,7 +409,7 @@ paths:
                   description: a list of domains for which a dkim key should be generated
                   type: string
                 key_size:
-                  description: the key size (1024 or 2048)
+                  description: the key size (1024, 2048, 3072 or 4096)
                   type: number
               type: object
       summary: Generate DKIM Key
diff --git a/data/web/inc/functions.dkim.inc.php b/data/web/inc/functions.dkim.inc.php
index 8b1766a20..e7e411730 100644
--- a/data/web/inc/functions.dkim.inc.php
+++ b/data/web/inc/functions.dkim.inc.php
@@ -240,9 +240,12 @@ function dkim($_action, $_data = null, $privkey = false) {
         if (strlen($dkimdata['pubkey']) < 391) {
           $dkimdata['length'] = "1024";
         }
-        elseif (strlen($dkimdata['pubkey']) < 736) {
+        elseif (strlen($dkimdata['pubkey']) < 564) {
           $dkimdata['length'] = "2048";
         }
+        elseif (strlen($dkimdata['pubkey']) < 736) {
+          $dkimdata['length'] = "3072";
+        }
         elseif (strlen($dkimdata['pubkey']) < 1416) {
           $dkimdata['length'] = "4096";
         }
diff --git a/data/web/templates/admin/tab-config-dkim.twig b/data/web/templates/admin/tab-config-dkim.twig
index 85c6dc6ae..ec77139ed 100644
--- a/data/web/templates/admin/tab-config-dkim.twig
+++ b/data/web/templates/admin/tab-config-dkim.twig
@@ -117,6 +117,8 @@
             <select data-style="btn btn-light btn-sm" class="form-control" id="key_size" name="key_size" title="{{ lang.admin.dkim_key_length }}" required>
               <option data-subtext="bits">1024</option>
               <option data-subtext="bits">2048</option>
+              <option data-subtext="bits">3072</option>
+              <option data-subtext="bits">4096</option>
             </select>
           </div>
         </div>
diff --git a/data/web/templates/edit/domain-templates.twig b/data/web/templates/edit/domain-templates.twig
index 825e6674d..d4612a198 100644
--- a/data/web/templates/edit/domain-templates.twig
+++ b/data/web/templates/edit/domain-templates.twig
@@ -103,6 +103,8 @@
         <select data-style="btn btn-light" class="form-control" id="key_size" name="key_size">
           <option value="1024" data-subtext="bits" {% if template.attributes.key_size == 1024 %} selected{% endif %}>1024</option>
           <option value="2048" data-subtext="bits" {% if template.attributes.key_size == 2048 %} selected{% endif %}>2048</option>
+          <option value="3072" data-subtext="bits" {% if template.attributes.key_size == 3072 %} selected{% endif %}>3072</option>
+          <option value="4096" data-subtext="bits" {% if template.attributes.key_size == 4096 %} selected{% endif %}>4096</option>
         </select>
       </div>
     </div>
diff --git a/data/web/templates/modals/mailbox.twig b/data/web/templates/modals/mailbox.twig
index 0f1b23a7e..76f54ec31 100644
--- a/data/web/templates/modals/mailbox.twig
+++ b/data/web/templates/modals/mailbox.twig
@@ -490,6 +490,8 @@
               <select data-style="btn btn-light" class="form-control" id="key_size" name="key_size">
                 <option data-subtext="bits" value="1024">1024</option>
                 <option data-subtext="bits" value="2048" selected>2048</option>
+                <option data-subtext="bits" value="3072">3072</option>
+                <option data-subtext="bits" value="4096">4096</option>
               </select>
             </div>
           </div>
@@ -628,6 +630,8 @@
               <select data-style="btn btn-light" class="form-control" id="key_size" name="key_size">
                 <option data-subtext="bits">1024</option>
                 <option data-subtext="bits" selected>2048</option>
+                <option data-subtext="bits">3072</option>
+                <option data-subtext="bits">4096</option>
               </select>
             </div>
           </div>
@@ -843,6 +847,8 @@
               <select data-style="btn btn-light" class="form-control" id="key_size2" name="key_size">
                 <option data-subtext="bits">1024</option>
                 <option data-subtext="bits" selected>2048</option>
+                <option data-subtext="bits">3072</option>
+                <option data-subtext="bits">4096</option>
               </select>
             </div>
           </div>