diff --git a/src/app/tabs/dashboard.component.ts b/src/app/tabs/dashboard.component.ts
index 030814a6..24b4cf87 100644
--- a/src/app/tabs/dashboard.component.ts
+++ b/src/app/tabs/dashboard.component.ts
@@ -15,7 +15,7 @@ export class DashboardComponent {
     constructor(private i18nService: I18nService, private syncService: SyncService) { }
 
     async sync() {
-        await this.syncService.sync(true, true);
+        await this.syncService.sync(false, true);
     }
 
     async simulate() {
diff --git a/src/services/azure-directory.service.ts b/src/services/azure-directory.service.ts
index 01e33b85..0ec98861 100644
--- a/src/services/azure-directory.service.ts
+++ b/src/services/azure-directory.service.ts
@@ -1,4 +1,5 @@
 import * as graph from '@microsoft/microsoft-graph-client';
+import * as graphType from '@microsoft/microsoft-graph-types';
 import * as https from 'https';
 import * as querystring from 'querystring';
 
@@ -12,12 +13,168 @@ import { UserEntry } from '../models/userEntry';
 import { ConfigurationService } from './configuration.service';
 import { DirectoryService } from './directory.service';
 
+const NextLink = '@odata.nextLink';
+const DeltaLink = '@odata.deltaLink';
+
 export class AzureDirectoryService implements DirectoryService {
     private client: graph.Client;
     private dirConfig: AzureConfiguration;
     private syncConfig: SyncConfiguration;
 
     constructor(private configurationService: ConfigurationService) {
+        this.init();
+    }
+
+    async getEntries(force = false): Promise<[GroupEntry[], UserEntry[]]> {
+        const type = await this.configurationService.getDirectoryType();
+        if (type !== DirectoryType.AzureActiveDirectory) {
+            return;
+        }
+
+        this.dirConfig = await this.configurationService.getDirectory<AzureConfiguration>(
+            DirectoryType.AzureActiveDirectory);
+        if (this.dirConfig == null) {
+            return;
+        }
+
+        this.syncConfig = await this.configurationService.getSync();
+        if (this.syncConfig == null) {
+            return;
+        }
+
+        let users: UserEntry[];
+        if (this.syncConfig.users) {
+            users = await this.getUsers(force);
+        }
+
+        let groups: GroupEntry[];
+        if (this.syncConfig.groups) {
+            groups = await this.getGroups();
+        }
+
+        return [groups, users];
+    }
+
+    private async getUsers(force: boolean): Promise<UserEntry[]> {
+        const entries: UserEntry[] = [];
+
+        let res: any = null;
+        const token = await this.configurationService.getUserDeltaToken();
+        if (!force && token != null) {
+            try {
+                const deltaReq = this.client.api(token);
+                res = await deltaReq.get();
+            } catch {
+                res = null;
+            }
+        }
+
+        if (res == null) {
+            const userReq = this.client.api('/users/delta');
+            res = await userReq.get();
+        }
+
+        const filter = this.createSet(this.syncConfig.userFilter);
+        while (true) {
+            const users: graphType.User[] = res.val;
+            if (users != null) {
+                users.forEach((user) => {
+                    const entry = new UserEntry();
+                    entry.referenceId = user.id;
+                    entry.externalId = user.id;
+                    entry.email = user.mail || user.userPrincipalName;
+                    entry.disabled = user.accountEnabled == null ? false : !user.accountEnabled;
+
+                    if (this.filterOutResult(filter, entry.email)) {
+                        return;
+                    }
+
+                    if ((user as any)['@removed'] != null && (user as any)['@removed'].reason === 'changed') {
+                        entry.deleted = true;
+                    } else if (!entry.disabled && (entry.email == null || entry.email.indexOf('#') > -1)) {
+                        return;
+                    }
+
+                    entries.push(entry);
+                });
+            }
+
+            if (res[NextLink] == null) {
+                if (res[DeltaLink] != null) {
+                    await this.configurationService.saveUserDeltaToken(res[DeltaLink]);
+                }
+                break;
+            } else {
+                const nextReq = this.client.api(res[NextLink]);
+                res = await nextReq.get();
+            }
+        }
+
+        return entries;
+    }
+
+    private async getGroups(): Promise<GroupEntry[]> {
+        const entries: GroupEntry[] = [];
+
+        const request = this.client.api('/groups/delta');
+        const groups = await request.get();
+        console.log(groups);
+
+        groups.value.forEach(async (g: any) => {
+            const membersRequest = this.client.api('/groups/' + g.id + '/members');
+            const members = await membersRequest.get();
+            console.log(members);
+        });
+
+        return entries;
+    }
+
+    private createSet(filter: string): [boolean, Set<string>] {
+        if (filter == null || filter === '') {
+            return null;
+        }
+
+        const parts = filter.split(':');
+        if (parts.length !== 2) {
+            return null;
+        }
+
+        const keyword = parts[0].trim().toLowerCase();
+        let exclude = true;
+        if (keyword === 'include') {
+            exclude = false;
+        } else if (keyword === 'exclude') {
+            exclude = true;
+        } else {
+            return null;
+        }
+
+        const set = new Set<string>();
+        const pieces = parts[1].split(',');
+        pieces.forEach((p) => {
+            set.add(p.trim().toLowerCase());
+        });
+
+        return [exclude, set];
+    }
+
+    private filterOutResult(filter: [boolean, Set<string>], result: string) {
+        if (filter != null) {
+            result = result.trim().toLowerCase();
+            const excluded = filter[0];
+            const set = filter[1];
+
+            if (excluded && set.has(result)) {
+                return true;
+            } else if (!excluded && !set.has(result)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+
+    private init() {
         this.client = graph.Client.init({
             authProvider: (done) => {
                 const data = querystring.stringify({
@@ -56,45 +213,4 @@ export class AzureDirectoryService implements DirectoryService {
             },
         });
     }
-
-    async getEntries(force = false): Promise<[GroupEntry[], UserEntry[]]> {
-        const type = await this.configurationService.getDirectoryType();
-        if (type !== DirectoryType.AzureActiveDirectory) {
-            return;
-        }
-
-        this.dirConfig = await this.configurationService.getDirectory<AzureConfiguration>(
-            DirectoryType.AzureActiveDirectory);
-        if (this.dirConfig == null) {
-            return;
-        }
-
-        this.syncConfig = await this.configurationService.getSync();
-        if (this.syncConfig == null) {
-            return;
-        }
-
-        await this.getUsers();
-        await this.getGroups();
-
-        return null;
-    }
-
-    private async getUsers() {
-        const request = this.client.api('/users/delta');
-        const users = await request.get();
-        console.log(users);
-    }
-
-    private async getGroups() {
-        const request = this.client.api('/groups/delta');
-        const groups = await request.get();
-        console.log(groups);
-
-        groups.value.forEach(async (g: any) => {
-            const membersRequest = this.client.api('/groups/' + g.id + '/members');
-            const members = await membersRequest.get();
-            console.log(members);
-        });
-    }
 }
diff --git a/src/services/configuration.service.ts b/src/services/configuration.service.ts
index b100d0c7..2a30cca6 100644
--- a/src/services/configuration.service.ts
+++ b/src/services/configuration.service.ts
@@ -14,6 +14,8 @@ const Keys = {
     directoryConfigPrefix: 'directoryConfig_',
     sync: 'syncConfig',
     directoryType: 'directoryType',
+    userDelta: 'userDeltaToken',
+    groupDelta: 'groupDeltaToken',
 };
 
 export class ConfigurationService {
@@ -73,19 +75,48 @@ export class ConfigurationService {
         await this.storageService.save(Keys.directoryConfigPrefix + type, savedConfig);
     }
 
-    async getSync(): Promise<SyncConfiguration> {
+    getSync(): Promise<SyncConfiguration> {
         return this.storageService.get<SyncConfiguration>(Keys.sync);
     }
 
-    async saveSync(config: SyncConfiguration) {
+    saveSync(config: SyncConfiguration) {
         return this.storageService.save(Keys.sync, config);
     }
 
-    async getDirectoryType(): Promise<DirectoryType> {
+    getDirectoryType(): Promise<DirectoryType> {
         return this.storageService.get<DirectoryType>(Keys.directoryType);
     }
 
     async saveDirectoryType(type: DirectoryType) {
+        const currentType = await this.getDirectoryType();
+        if (type !== currentType) {
+            await this.saveUserDeltaToken(null);
+            await this.saveGroupDeltaToken(null);
+        }
         return this.storageService.save(Keys.directoryType, type);
     }
+
+    getUserDeltaToken(): Promise<string> {
+        return this.storageService.get<string>(Keys.userDelta);
+    }
+
+    saveUserDeltaToken(token: string) {
+        if (token == null) {
+            return this.storageService.remove(Keys.userDelta);
+        } else {
+            return this.storageService.save(Keys.userDelta, token);
+        }
+    }
+
+    getGroupDeltaToken(): Promise<string> {
+        return this.storageService.get<string>(Keys.groupDelta);
+    }
+
+    saveGroupDeltaToken(token: string) {
+        if (token == null) {
+            return this.storageService.remove(Keys.groupDelta);
+        } else {
+            return this.storageService.save(Keys.groupDelta, token);
+        }
+    }
 }