diff --git a/src/clientManager.js b/src/clientManager.js
index 7aa8315d..ca1f55b6 100644
--- a/src/clientManager.js
+++ b/src/clientManager.js
@@ -6,6 +6,7 @@ const colors = require("chalk");
 const crypto = require("crypto");
 const fs = require("fs");
 const path = require("path");
+const Auth = require("./plugins/auth");
 const Client = require("./client");
 const Helper = require("./helper");
 const WebPush = require("./plugins/webpush");
@@ -45,7 +46,15 @@ ClientManager.prototype.loadUsers = function () {
 		);
 	}
 
-	users.forEach((name) => this.loadUser(name));
+	// This callback is used by Auth plugins to load users they deem acceptable
+	const callbackLoadUser = (user) => {
+		this.loadUser(user);
+	};
+
+	if (!Auth.loadUsers(users, callbackLoadUser)) {
+		// Fallback to loading all users
+		users.forEach((name) => this.loadUser(name));
+	}
 };
 
 ClientManager.prototype.autoloadUsers = function () {
diff --git a/src/plugins/auth.js b/src/plugins/auth.js
new file mode 100644
index 00000000..6e951010
--- /dev/null
+++ b/src/plugins/auth.js
@@ -0,0 +1,50 @@
+"use strict";
+
+const log = require("../log");
+const colors = require("chalk");
+
+// The order defines priority: the first available plugin is used.
+// Always keep 'local' auth plugin at the end of the list; it should always be enabled.
+const plugins = [require("./auth/ldap"), require("./auth/local")];
+
+function unimplemented(funcName) {
+	log.debug(
+		`Auth module ${colors.bold(
+			module.exports.moduleName
+		)} doesn't implement function ${colors.bold(funcName)}`
+	);
+}
+
+// Default API implementations
+module.exports = {
+	moduleName: "<module with no name>",
+
+	// Must override: implements authentication mechanism
+	auth: () => unimplemented("auth"),
+
+	// Optional to override: implements filter for loading users at start up
+	// This allows an auth plugin to check if a user is still acceptable, if the plugin
+	// can do so without access to the user's unhashed password.
+	// Returning 'false' triggers fallback to default behaviour of loading all users
+	loadUsers: () => false,
+};
+
+// local auth should always be enabled, but check here to verify
+let somethingEnabled = false;
+
+// Override default API stubs with exports from first enabled plugin found
+for (const plugin of plugins) {
+	if (plugin.isEnabled()) {
+		somethingEnabled = true;
+
+		for (const name in plugin) {
+			module.exports[name] = plugin[name];
+		}
+
+		break;
+	}
+}
+
+if (!somethingEnabled) {
+	log.error("None of the auth plugins is enabled");
+}
diff --git a/src/plugins/auth/ldap.js b/src/plugins/auth/ldap.js
index 18441e5e..1c93419f 100644
--- a/src/plugins/auth/ldap.js
+++ b/src/plugins/auth/ldap.js
@@ -3,6 +3,7 @@
 const log = require("../../log");
 const Helper = require("../../helper");
 const ldap = require("ldapjs");
+const colors = require("chalk");
 
 function ldapAuthCommon(user, bindDN, password, callback) {
 	const config = Helper.config;
@@ -77,41 +78,42 @@ function advancedLdapAuth(user, password, callback) {
 			log.error("Invalid LDAP root credentials");
 			ldapclient.unbind();
 			callback(false);
-		} else {
-			ldapclient.search(base, searchOptions, function (err2, res) {
-				if (err2) {
-					log.warn(`LDAP User not found: ${userDN}`);
-					ldapclient.unbind();
+			return;
+		}
+
+		ldapclient.search(base, searchOptions, function (err2, res) {
+			if (err2) {
+				log.warn(`LDAP User not found: ${userDN}`);
+				ldapclient.unbind();
+				callback(false);
+				return;
+			}
+
+			let found = false;
+
+			res.on("searchEntry", function (entry) {
+				found = true;
+				const bindDN = entry.objectName;
+				log.info(`Auth against LDAP ${config.ldap.url} with found bindDN ${bindDN}`);
+				ldapclient.unbind();
+
+				ldapAuthCommon(user, bindDN, password, callback);
+			});
+
+			res.on("error", function (err3) {
+				log.error(`LDAP error: ${err3}`);
+				callback(false);
+			});
+
+			res.on("end", function (result) {
+				ldapclient.unbind();
+
+				if (!found) {
+					log.warn(`LDAP Search did not find anything for: ${userDN} (${result.status})`);
 					callback(false);
-				} else {
-					let found = false;
-					res.on("searchEntry", function (entry) {
-						found = true;
-						const bindDN = entry.objectName;
-						log.info(
-							`Auth against LDAP ${config.ldap.url} with found bindDN ${bindDN}`
-						);
-						ldapclient.unbind();
-
-						ldapAuthCommon(user, bindDN, password, callback);
-					});
-					res.on("error", function (err3) {
-						log.error(`LDAP error: ${err3}`);
-						callback(false);
-					});
-					res.on("end", function (result) {
-						ldapclient.unbind();
-
-						if (!found) {
-							log.warn(
-								`LDAP Search did not find anything for: ${userDN} (${result.status})`
-							);
-							callback(false);
-						}
-					});
 				}
 			});
-		}
+		});
 	});
 }
 
@@ -139,11 +141,94 @@ function ldapAuth(manager, client, user, password, callback) {
 	return auth(user, password, callbackWrapper);
 }
 
+/**
+ * Use the LDAP filter from config to check that users still exist before loading them
+ * via the supplied callback function.
+ */
+
+function advancedLdapLoadUsers(users, callbackLoadUser) {
+	const config = Helper.config;
+
+	const ldapclient = ldap.createClient({
+		url: config.ldap.url,
+		tlsOptions: config.ldap.tlsOptions,
+	});
+
+	const base = config.ldap.searchDN.base;
+
+	ldapclient.on("error", function (err) {
+		log.error(`Unable to connect to LDAP server: ${err}`);
+	});
+
+	ldapclient.bind(config.ldap.searchDN.rootDN, config.ldap.searchDN.rootPassword, function (err) {
+		if (err) {
+			log.error("Invalid LDAP root credentials");
+			return true;
+		}
+
+		const remainingUsers = new Set(users);
+
+		const searchOptions = {
+			scope: config.ldap.searchDN.scope,
+			filter: `${config.ldap.searchDN.filter}`,
+			attributes: [config.ldap.primaryKey],
+			paged: true,
+		};
+
+		ldapclient.search(base, searchOptions, function (err2, res) {
+			if (err2) {
+				log.error(`LDAP search error: ${err2}`);
+				return true;
+			}
+
+			res.on("searchEntry", function (entry) {
+				const user = entry.attributes[0]._vals[0].toString();
+
+				if (remainingUsers.has(user)) {
+					remainingUsers.delete(user);
+					callbackLoadUser(user);
+				}
+			});
+
+			res.on("error", function (err3) {
+				log.error(`LDAP error: ${err3}`);
+			});
+
+			res.on("end", function () {
+				remainingUsers.forEach((user) => {
+					log.warn(
+						`No account info in LDAP for ${colors.bold(
+							user
+						)} but user config file exists`
+					);
+				});
+			});
+		});
+
+		ldapclient.unbind();
+	});
+
+	return true;
+}
+
+function ldapLoadUsers(users, callbackLoadUser) {
+	if ("baseDN" in Helper.config.ldap) {
+		// simple LDAP case can't test for user existence without access to the
+		// user's unhashed password, so indicate need to fallback to default
+		// loadUser behaviour by returning false
+		return false;
+	}
+
+	return advancedLdapLoadUsers(users, callbackLoadUser);
+}
+
 function isLdapEnabled() {
 	return !Helper.config.public && Helper.config.ldap.enable;
 }
 
 module.exports = {
+	moduleName: "ldap",
 	auth: ldapAuth,
 	isEnabled: isLdapEnabled,
+	loadUsers: ldapLoadUsers,
 };
diff --git a/src/plugins/auth/local.js b/src/plugins/auth/local.js
index e5ff367c..1b062f31 100644
--- a/src/plugins/auth/local.js
+++ b/src/plugins/auth/local.js
@@ -46,6 +46,7 @@ function localAuth(manager, client, user, password, callback) {
 }
 
 module.exports = {
+	moduleName: "local",
 	auth: localAuth,
 	isEnabled: () => true,
 };
diff --git a/src/server.js b/src/server.js
index a4030843..f41554a2 100644
--- a/src/server.js
+++ b/src/server.js
@@ -17,16 +17,13 @@ const net = require("net");
 const Identification = require("./identification");
 const changelog = require("./plugins/changelog");
 const inputs = require("./plugins/inputs");
+const Auth = require("./plugins/auth");
 
 const themes = require("./plugins/packages/themes");
 themes.loadLocalThemes();
 
 const packages = require("./plugins/packages/index");
 
-// The order defined the priority: the first available plugin is used
-// ALways keep local auth in the end, which should always be enabled.
-const authPlugins = [require("./plugins/auth/ldap"), require("./plugins/auth/local")];
-
 // A random number that will force clients to reload the page if it differs
 const serverHash = Math.floor(Date.now() * Math.random());
 
@@ -851,18 +848,7 @@ function performAuthentication(data) {
 	}
 
 	// Perform password checking
-	let auth = () => {
-		log.error("None of the auth plugins is enabled");
-	};
-
-	for (let i = 0; i < authPlugins.length; ++i) {
-		if (authPlugins[i].isEnabled()) {
-			auth = authPlugins[i].auth;
-			break;
-		}
-	}
-
-	auth(manager, client, data.user, data.password, authCallback);
+	Auth.auth(manager, client, data.user, data.password, authCallback);
 }
 
 function reverseDnsLookup(ip, callback) {