If you have numerous spaces in Confluence and would like to check for spaces which have a mail setting, you can run a database query like the one below:

select spaces.spacename, spaces.spacekey, bandana.bandanakey
from spaces, bandana 
where spaces.spacekey = bandana.bandanacontext AND bandana.bandanakey="atlassian.confluence.space.mailaccounts";
関連トピック

How do I Disable Automatic Mail Polling?