I have enables the option " Open email before sending". But when I click continue to send an email from sales order confirmation. It always downloading the .eml file instead of previewing.
The “Open email before sending” option downloads the .eml file in the browser when generating the report, containing everything that would be included in the email. This allows you to review the content before deciding whether to send it. If no changes are needed, you can send it; if not, you can choose not to. This option effectively serves as a built-in preview feature.