IMAP and POP are two different protocols that allow you to download the emails from your Server and access them from the email clients of your choice. The protocols allow you to access the Zoho Mail account from desktop clients like Outlook or from mobile devices like iPhone. Zoho Mail can be configured in any standard IMAP email client providing the IMAP and SMTP server settings.
IMAP is the most recent protocol than POP. IMAP allows a two way synchronization between the email client you use and your Zoho Mail account. IMAP is also recomended when you want to access the same account from multiple email clients.
Zoho Mail can be accessed via IMAP in any standard IMAP clients using the configuration details provided in this page. You have to Enable IMAP Access for your account before you begin the configuration in the email clients. The step by step instructions for some of the popular IMAP clients are available in the links below.
Desktop Clients: Outlook | Thunderbird | Apple iMac Mail | Other IMAP Clients
Mobile Devices/ Tablets: Apple iPhone/iPad | Windows 7 Mobile | Android (Samsung, Google Nexus etc) | Other mobile IMAP Clients

You can configure your Zoho Mail account in any standard IMAP client. The required configuration details for accessing Zoho Mail account via IMAP are given below.
Incoming Server Settings:
Incoming Server Name: imap.zoho.com
Port: 993
Require SSL: Yes
Outgoing Server Settings:
Outgoing Server Name: smtp.zoho.com
Port: 465
Require SSL: Yes
Require Authentication: Yes
User Name : Zoho user name or Your complete Zoho Mail address. If your domain is hosted with Zoho, then provide you@yourdomain.com here.
Email Address : Your Zoho email Address. If your domain is hosted with Zoho, provide you@yourdomain.com.
Password: Your Zoho account password.
Note: If you are a Federated Sign In user, you will not have a 'Zoho' password for your account. Use the Forgot Password link in the login page, to generate Zoho specific password for your account in Zoho. The Federated Login credentials will not work for POP/ IMAP/ Active Sync access.
You can optimize the performance of your IMAP client by choosing the folders you want to synchronize in IMAP. If you have a huge mailbox with a lot of folders, viewing and synchronizing all folders in IMAP clients like iPhone may be time consuming and cumbersome due to the size of data. You can choose the folders, which you want to sync in IMAP.

When you delete or move an email in your IMAP client, the email is marked for deletion in the current folder and copied to the destination folder or Trash folder based on the IMAP settings. You can enable the option 'Expunge immediately' for such changes to be immediately effective in your IMAP account. Again this is based on the IMAP Client behavior and how it sends requests to the Server.