You need to brand emails or documents you send to your clients? You would like to start your letters with 'Hello YourClientName' instead of 'To Whom It May Concern'?
You can build email and document templates in Zoho with your Logo/pictures and with special 'merge' fields, such as CustomerName, CustomerItems. Those fields will be replaced for 'Susan', 'T-Shirts' and whatever you have in your client profile / invoice etc. You do not need to do it manually any more.
However, say, you would like to customize your emails for mobile devices? For example, to have a big font if your client opens it on iPhone? More than 60% emails are opened on gadgets. Is it possible to manage it?
There are some advanced tools for templates with Zoho. Mobile responsive design, building complex emails and documents 'on-the-fly' etc - whatever is needed.