See also How to Set Up Zimbra Desktop
See also Zimbra with Outlook
Some application software has the ability to send e-mail from within the app. Some common apps that can send mail are:
Apps like these do not generally have the ability to send e-mail themselves. They generally use a full e-mail client installed on the workstation to do the sending for them.
Applications do not generally have the ability to use the Zimbra Web Client (or any webmail client, for that matter). So, if you use the Zimbra Web Client as your primary e-mail client, and you need to send e-mail from within another app, you will need to install and configure a full e-mail client app on your workstation.
You can often use an app already installed on your PC, such as Microsoft Outlook, or other free mail client apps such as Mozilla Thunderbird or Zimbra Desktop.
Generally, only Zimbra Desktop will provide full Zimbra functionality, if you were to use it as your primary mail client.
Frequently, we just configure the full e-mail client app to be used only to send from within your target app (i.e. Quickbooks) and we continue to use the Zimbra Web Client as our primary mail client.
Suggestions:
If you just want to send mail from within an app, and Microsoft Outlook is already installed on your PC, just configure Outlook with an IMAP account.
If you want full Zimbra functionality in a full Desktop e-mail client, install and configure the free Zimbra Desktop.