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Signature preview not working in Outlook


You experience problems with CodeTwo Email Signatures for Office 365 Add-in in Outlook and Outlook on the web (OWA). For example, the add-in button does not appear in the new email window, is inactive (Fig. 1.) or, in general, the add-in does not work as expected. 

Fig. 1. Inactive add-in button in the Outlook’s new email window.


Since signatures are added on the server, they are added even if the preview add-in is not deployed or does not work.


Issues with CodeTwo Email Signatures for Office 365 Add-in can be caused by several factors. Follow the links below to find a solution that works best in your environment:

Multiple add-ins installed on the same client are incompatible with each other

There are several types of Outlook add-ins, and some of them might interfere with each other. Older types of add-ins, such as COM add-ins, can be incompatible with newer types of add-ins, such as web add-ins. CodeTwo Email Signatures for Office 365 Add-in is an example of a modern web add-in and – unlike COM add-ins – it does not install any code on your machine.

In rare cases, you may need to disable a COM add-in, especially if it uses custom forms, for CodeTwo Email Signatures for Office 365 Add-in to work properly.

To find out which COM add-in causes the issue, you first need to disable all the COM add-ins that you installed (you don’t need to disable the add-ins that are installed by default by Microsoft, such as Microsoft Exchange Add-in) and then enable them again one by one. Remember to restart Outlook after re-enabling each add-in and check if CodeTwo Email Signatures for Office 365 Add-in is active.

To disable and re-enable a COM add-in:

  1. In Outlook, go to File > Options > Add-ins
  2. In the Manage section at the bottom of the window, choose COM Add-ins and click Go (Fig. 2.).

Fig. 2. Selecting COM Add-ins.

  1. In the window that opens, clear (deselect) the checkboxes for the add-ins that you want to disable and click OK. (Fig. 3.).

Fig. 3. A list of Outlook COM add-ins. To disable an add-in, clear its checkbox.

  1. Re-enable the disabled add-ins one by one by selecting (checking) them again and restarting Outlook each time to see if the signature preview is working.

After finding out which add-in is the source of the problem, disable it whenever you want to preview your signatures.

CodeTwo domain is blocked by antivirus software

To display a preview of the signature, CodeTwo Email Signatures for Office 365 Add-in needs to access two web locations:

Your antivirus software may be set to block connections to any domain outside its list of trusted domains. Make sure that you add the address of your geolocation and of the add-in to trusted domains in your antivirus software.

Outlook version is not supported

CodeTwo Email Signatures for Office 365 Add-in works with all 32- and 64-bit versions of Outlook 2013 and newer. However, to use this add-in in Outlook 2013, you need to update Outlook 2013 to the newest version.

The add-in also works with Outlook 2016 for Mac and Outlook on the web (OWA).

A detailed list of requirements is available in the User’s manual.




  • Applies to: CodeTwo Email Signatures for Office 365 1.x
  • Categories: Troubleshooting
  • Last modified: 2018-03-06
  • Created: 2017-12-21
  • ID: 670
  • Keywords: signature preview, not working, grey button, add-in not working, no signature preview, inactive signature preview, signature preview not visible
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