diff --git a/_modules/scripts/new_options.sh b/_modules/scripts/new_options.sh
index 840700148..7d67799ba 100644
--- a/_modules/scripts/new_options.sh
+++ b/_modules/scripts/new_options.sh
@@ -60,6 +60,7 @@ adapt_new_options() {
   "ACME_DNS_CHALLENGE"
   "ACME_DNS_PROVIDER"
   "ACME_ACCOUNT_EMAIL"
+  "NGINX_MAX_BODY_SIZE"
   )
 
   sed -i --follow-symlinks '$a\' mailcow.conf
@@ -309,6 +310,11 @@ adapt_new_options() {
             echo '# Account email for ACME DNS-01 challenge registration' >> mailcow.conf
             echo 'ACME_ACCOUNT_EMAIL=me@example.com' >> mailcow.conf
             ;;
+        NGINX_MAX_BODY_SIZE)
+            echo '# Maximum request size for SOGo webmail, CalDAV/CardDAV and ActiveSync, e.g. 128m or 1g - 0 means unlimited' >> mailcow.conf
+            echo '# Keep it above the message size limit of Postfix (100 MB by default). The mailcow UI and API stay limited to 64m.' >> mailcow.conf
+            echo 'NGINX_MAX_BODY_SIZE=128m' >> mailcow.conf
+            ;;
         *)
             echo "${option}=" >> mailcow.conf
             ;;
diff --git a/data/Dockerfiles/nginx/bootstrap.py b/data/Dockerfiles/nginx/bootstrap.py
index 97ce7a4e1..b48b26f50 100644
--- a/data/Dockerfiles/nginx/bootstrap.py
+++ b/data/Dockerfiles/nginx/bootstrap.py
@@ -1,4 +1,5 @@
 import os
+import re
 import subprocess
 from jinja2 import Environment, FileSystemLoader
 
@@ -44,6 +45,11 @@ def prepare_template_vars():
   ipv4_network = os.getenv("IPV4_NETWORK", "172.22.1")
   additional_server_names = os.getenv("ADDITIONAL_SERVER_NAMES", "")
   trusted_proxies = os.getenv("TRUSTED_PROXIES", "")
+  # nginx size syntax, invalid values fall back to the default
+  max_body_size = os.getenv("NGINX_MAX_BODY_SIZE", "128m").strip()
+  if not re.fullmatch(r'[0-9]+[kKmMgG]?', max_body_size):
+    print(f"Invalid NGINX_MAX_BODY_SIZE '{max_body_size}', using 128m")
+    max_body_size = "128m"
 
   template_vars = {
     'IPV4_NETWORK': ipv4_network,
@@ -60,6 +66,7 @@ def prepare_template_vars():
     'PHPFPMHOST': os.getenv("PHPFPMHOST", "php-fpm-mailcow"),
     'ENABLE_IPV6': os.getenv("ENABLE_IPV6", "true").lower() != "false",
     'HTTP_REDIRECT': os.getenv("HTTP_REDIRECT", "n").lower() in ("y", "yes"),
+    'NGINX_MAX_BODY_SIZE': max_body_size,
   }
 
   ssl_dir = '/etc/ssl/mail/'
diff --git a/data/conf/nginx/templates/sites-default.conf.j2 b/data/conf/nginx/templates/sites-default.conf.j2
index 9cd60a343..2082c6822 100644
--- a/data/conf/nginx/templates/sites-default.conf.j2
+++ b/data/conf/nginx/templates/sites-default.conf.j2
@@ -22,7 +22,8 @@ add_header Referrer-Policy strict-origin;
 
 index index.php index.html;
 
-client_max_body_size 0;
+# PHP accepts no larger requests (post_max_size), SOGo webmail, CalDAV/CardDAV and ActiveSync use NGINX_MAX_BODY_SIZE
+client_max_body_size 64m;
 
 gzip on;
 gzip_disable "msie6";
@@ -182,6 +183,8 @@ location /sogo-auth-verify {
     proxy_set_header  Content-Length "";
     proxy_pass        http://127.0.0.1:65510/sogo-auth;
     proxy_pass_request_body off;
+    # The subrequest checks the size of the original request against this limit, the body is never read here
+    client_max_body_size {{ NGINX_MAX_BODY_SIZE }};
 }
 
 location ^~ /Microsoft-Server-ActiveSync {
@@ -205,7 +208,7 @@ location ^~ /Microsoft-Server-ActiveSync {
     proxy_busy_buffers_size 512k;
     proxy_set_header Host $http_host;
     client_body_buffer_size 512k;
-    client_max_body_size 0;
+    client_max_body_size {{ NGINX_MAX_BODY_SIZE }};
 }
 
 location ^~ /SOGo {
@@ -256,7 +259,7 @@ location ^~ /SOGo {
     proxy_send_timeout 3600;
     proxy_read_timeout 3600;
     client_body_buffer_size 128k;
-    client_max_body_size 0;
+    client_max_body_size {{ NGINX_MAX_BODY_SIZE }};
     break;
 }
 
diff --git a/docker-compose.yml b/docker-compose.yml
index c77c7baaa..4e2598ed8 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -427,7 +427,7 @@ services:
         - php-fpm-mailcow
         - sogo-mailcow
         - rspamd-mailcow
-      image: ghcr.io/mailcow/nginx:1.30.6-1
+      image: ghcr.io/mailcow/nginx:1.30.6-2
       dns:
         - ${IPV4_NETWORK:-172.22.1}.254
       environment:
@@ -447,6 +447,7 @@ services:
         - IPV4_NETWORK=${IPV4_NETWORK:-172.22.1}
         - NGINX_USE_PROXY_PROTOCOL=${NGINX_USE_PROXY_PROTOCOL:-n}
         - TRUSTED_PROXIES=${TRUSTED_PROXIES:-}
+        - NGINX_MAX_BODY_SIZE=${NGINX_MAX_BODY_SIZE:-128m}
       volumes:
         - ./data/web:/web:ro,z
         - ./data/conf/rspamd/dynmaps:/dynmaps:ro,z
diff --git a/generate_config.sh b/generate_config.sh
index fe525b91b..5d76e5ea5 100755
--- a/generate_config.sh
+++ b/generate_config.sh
@@ -215,6 +215,10 @@ HTTPS_BIND=
 # Redirect HTTP connections to HTTPS - y/n
 HTTP_REDIRECT=y
 
+# Maximum request size for SOGo webmail, CalDAV/CardDAV and ActiveSync, e.g. 128m or 1g - 0 means unlimited
+# Keep it above the message size limit of Postfix (100 MB by default). The mailcow UI and API stay limited to 64m.
+NGINX_MAX_BODY_SIZE=128m
+
 # ------------------------------
 # Other bindings
 # ------------------------------