If you have configured the File Block Settings in Word to prevent specified types of files from being opened or saved, you cannot open or save these types of files in other Office components. Precisely speaking, Outlook signatures cannot be created and edited if the Web Pages, RTF Files, and Plain Text Files are forbidden to open or save in the File Block Settings in Word. You can fix it as follows:

1. Create a new Word document, and click File > Options.

2. In the opening Word Options dialog box, please click Trust Center in the left bar, and then click the Trust Center Settings button. See screenshot:

3. Now the Trust Center dialog box comes out, please click File Block Settings in the left bar, and uncheck all checkboxes beside Web Pages, RTF Files, and Plain Text Files in the right section. See screenshot:

4. Click the OK buttons twice to close two dialog boxes, and close the new document without saving.

From now on, all signatures in Outlook can be saved and edited regularly.

Open attachments without always asking in Outlook

Open attachments in edit mode (not read-only/protected view) in Outlook