diff --git a/core/admin/start.py b/core/admin/start.py
index 9574bbb7..24f31e07 100755
--- a/core/admin/start.py
+++ b/core/admin/start.py
@@ -64,7 +64,7 @@ test_unsupported()
 
 cmdline = [
     "gunicorn",
-    "--threads", f"{os.cpu_count()}",
+    "--threads", os.environ.get('CPU_COUNT', '1'),
     # If SUBNET6 is defined, gunicorn must listen on IPv6 as well as IPv4
     "-b", f"{'[::]' if os.environ.get('SUBNET6') else '0.0.0.0'}:8080",
     "--logger-class mailu.Logger",
diff --git a/core/base/libs/socrate/socrate/system.py b/core/base/libs/socrate/socrate/system.py
index c5046f4c..f494a7b7 100644
--- a/core/base/libs/socrate/socrate/system.py
+++ b/core/base/libs/socrate/socrate/system.py
@@ -141,6 +141,8 @@ def clean_env():
         for item in os.environ.get('TLS', ALL_PORTS).split(','):
             if item in PORTS_REQUIRING_TLS:
                 os.environ[f'TLS_{item}']='True'
+    if 'CPU_COUNT' not in os.environ:
+        os.environ['CPU_COUNT'] = str(os.cpu_count())
 
 def drop_privs_to(username='mailu'):
     pwnam = getpwnam(username)
diff --git a/core/dovecot/conf/dovecot.conf b/core/dovecot/conf/dovecot.conf
index 9c92aca6..03709b2e 100644
--- a/core/dovecot/conf/dovecot.conf
+++ b/core/dovecot/conf/dovecot.conf
@@ -137,12 +137,22 @@ service imap-login {
   inet_listener imap {
     port = 143
   }
+  service_count = 0
+  client_limit = 25000
+  process_min_avail = {{ CPU_COUNT }}
+  process_limit = {{ CPU_COUNT }}
+  vsz_limit = 256M
 }
 
 service pop3-login {
   inet_listener pop3 {
     port = 110
   }
+  service_count = 0
+  client_limit = 25000
+  process_min_avail = {{ CPU_COUNT }}
+  process_limit = {{ CPU_COUNT }}
+  vsz_limit = 256M
 }
 
 ###############
@@ -166,6 +176,11 @@ service managesieve-login {
   inet_listener sieve {
     port = 4190
   }
+  service_count = 0
+  client_limit = 25000
+  process_min_avail = {{ CPU_COUNT }}
+  process_limit = {{ CPU_COUNT }}
+  vsz_limit = 256M
 }
 
 protocol sieve {
@@ -223,4 +238,4 @@ service anvil {
 # Extensions
 ###############
 
-!include_try /overrides/dovecot.conf
+!include_try /overrides/dovecot/proxy.conf
diff --git a/core/nginx/dovecot/proxy.conf b/core/nginx/dovecot/proxy.conf
index 8decfc77..d7fcbb0a 100644
--- a/core/nginx/dovecot/proxy.conf
+++ b/core/nginx/dovecot/proxy.conf
@@ -87,6 +87,11 @@ service managesieve-login {
   inet_listener sieve-webmail {
     port = 14190
   }
+  service_count = 0
+  client_limit = 25000
+  process_min_avail = {{ CPU_COUNT }}
+  process_limit = {{ CPU_COUNT }}
+  vsz_limit = 256M
 }
 {% endif %}
 
@@ -114,6 +119,11 @@ service imap-login {
   inet_listener imap-webmail {
    port = 10143
   }
+  service_count = 0
+  client_limit = 25000
+  process_min_avail = {{ CPU_COUNT }}
+  process_limit = {{ CPU_COUNT }}
+  vsz_limit = 256M
 }
 
 service pop3-login {
@@ -132,6 +142,11 @@ service pop3-login {
 {% endif %}
   }
 {% endif %}
+  service_count = 0
+  client_limit = 25000
+  process_min_avail = {{ CPU_COUNT }}
+  process_limit = {{ CPU_COUNT }}
+  vsz_limit = 256M
 }
 
 recipient_delimiter = {{ RECIPIENT_DELIMITER }}
@@ -161,4 +176,11 @@ service submission-login {
    inet_listener submission-webmail {
     port = 10025
    }
+  service_count = 0
+  client_limit = 25000
+  process_min_avail = {{ CPU_COUNT }}
+  process_limit = {{ CPU_COUNT }}
+  vsz_limit = 256M
 }
+
+!include_try /overrides/dovecot.conf
diff --git a/docs/faq.rst b/docs/faq.rst
index 6b3011a1..1111481d 100644
--- a/docs/faq.rst
+++ b/docs/faq.rst
@@ -256,8 +256,10 @@ correct syntax. The following file names will be taken as override configuration
    - For both ``postfix.cf`` and ``postfix.master``, you need to put one configuration per line, as they are fed line-by-line
      to postfix.
    - ``logrotate.conf`` as ``$ROOT/overrides/postfix/logrotate.conf`` - Replaces the logrotate.conf file used for rotating ``POSTFIX_LOG_FILE``.
-- `Dovecot`_ - ``dovecot.conf`` in dovecot sub-directory;
-- `Nginx`_ - All ``*.conf`` files in the ``nginx`` sub-directory;
+- `Dovecot`_ - ``dovecot.conf`` in dovecot sub-directory.
+- `Nginx`_ :
+   - All ``*.conf`` files in the ``nginx`` sub-directory.
+   - ``proxy.conf`` in the ``nginx/dovecot`` sub-directory.
 - `Rspamd`_ - All files in the ``rspamd`` sub-directory.
 - `Roundcube`_ - All ``*.inc.php`` files in the ``roundcube`` sub directory.
 
diff --git a/towncrier/newsfragments/3450.bugfix b/towncrier/newsfragments/3450.bugfix
new file mode 100644
index 00000000..50c75f22
--- /dev/null
+++ b/towncrier/newsfragments/3450.bugfix
@@ -0,0 +1,2 @@
+Ensure we can do more than 100 parallel sessions.
+Allow dovecot's config to be overriden in front too