Added dovecot option for mail_max_userip_connections defaulting to 100

default.nix

@@ -414,6 +414,16 @@ in
       '';
     };
 
+    maxConnectionsPerUser = mkOption {
+      type = types.int;
+      default = 100;
+      description = ''
+        Maximum number of IMAP/POP3 connections allowed for a user from each IP address.
+        E.g. a value of 50 allows for 50 IMAP and 50 POP3 connections at the same
+        time for a single user.
+      '';
+    };
+
     localDnsResolver = mkOption {
       type = types.bool;
       default = true;

mail-server/dovecot.nix

@@ -67,6 +67,14 @@ in
           verbose_ssl = yes
         ''}
 
+        protocol imap {
+          mail_max_userip_connections = ${toString cfg.maxConnectionsPerUser}
+        }
+
+        protocol pop3 {
+          mail_max_userip_connections = ${toString cfg.maxConnectionsPerUser}
+        }
+
         mail_access_groups = ${vmailGroupName}
         ssl = required
         ${lib.optionalString (dovecotVersion.major == 2 && dovecotVersion.minor >= 3) ''