Email icon is not shown

Problem

After creating an issue, the email does not show the Jira icon.

Cause

a) You are using the Office 365 add-in, which does not support email icons

b) You have configured Outlook to hide the icon. To fix this, please check your view configuration:

1. In Outlook, go to "View" → "Arrangement" → "View Settings" → "Columns"
2. Make sure "Icon" is added: