At the moment, Confluence doesn't have any way to allow administrators to disable mail servers (they can only add/remove them) in the Confluence UI. Instead, a system property needs to be set at the JVM level to disable the mail server.

Adding this to the Confluence UI would allow Administrators to disable email servers as needed, for example if they wanted to bulk edit pages or spaces.

Workaround:

1. Stop Confluence
2. Add -Datlassian.mail.senddisabled=true to the JVM arguments for Confluence as described in Confluence System Properties
3. Start Confluence

This will only disable automated emails from being sent, it will not prevent test emails from being sent manually